(spoilers) First off, I want to say that I do not think that Demon Slayer has no substance or that's it's badly written per say. The thing is that Demon Slayer heavily rely on emotions to convey it's messages.

The indomitable human spirit against fatality/never giving up, teamwork/friendship/empathy, goals/purpose : all these messages are "classic" for the nekketsu shonen of SJ. Yet, what made KnY stands out is how it excelled at making you feel these messages. The grandiose hype-worthy fight scenes combined with the tragic backstories made people go insane for KnY. You just have to see the impact of the end of S1 or Rengoku's character on watchers. The insane work of Ufotable elevated the source material, making it one of the most captivating anime, at least for particular scenes.

Many dislike KnY because of it's weak plot structure but I think it was overshadowed by the incredible adaptation that made us feel crazy emotions infinitly superior to any logical grip we had for the anime.

But then... What's there left but the weak plot structure when the feelings are not conveyed to the watchers ?

The hashiras aren't the "pillars" of this arc.

Rengoku was irrefutably the face of the KnY movie. Tengen (and the antagonists but we'll get to that later) was the reason S2 was such a blast. The arc was written (partly) to highlight his character and the message he conveys. The pillars in these arcs weren't at the mercy of the arcs, the arcs existed for them. Now, can we really say the same for MItsuri and Muichirou ?

• Muichirou had his own separated fight and even though his flashback was intersting, the villain was such a boring, one and an half layered character that the fight just didn't caught my attention. Akaza is also a one layered chararcter with no depht (for now of course, we'll have his arc someday) but at least, efforts were made to make him interesting and to establish his "aura". This made him entertaining, he was written to be a one hit cool character and then be important in the future. Even if we didn't see much of him it makes sense he's popular since he was written in a way to make him interesting at his first appearance. Clearly, no efforts were made for the pot demon or whatever. Even his character design is non captivating and unwhorthy of a Demon Moon. It's just disappointing. Gyutaro & Daki actually brung some substance to KnY and were far more cooler.

• Mitsuri just felt useless in the fight. She basicaly just held off the villain off screen. I actually can't believe she had no spectacular scene except her flashback and we gotta talk about this. I'm actually conflicted about her backstory because I know a some people said it was an irrevelant story merely promoting feminism like "Yes I'm a girl but I can be strong and eat a lot too ehe". I don't think it's unrelated to KnY though, not even because of the era but because of S3 substance. This season is about personas, we realize that the eccentricity of the hashiras might not just be personality traits but a necessity for them to survive in this world. It makes us think about the previous hashiras, Rengoku had to keep his mentality to accept what he lost and what he couldn't change. Tengen clearly forced himself to act all flashy to make up for all the ugliness of his past. Is this just a cowardly way to cope or an act of bravoure to move on? What would the hashiras be wihtout their titles of hashiras ? Such were the questions raised. The fear demon used his persona (hands that "moved by themselves") because he coulnd't accept what he'd done. The brother of Muichirou put on a cold persona by fear to lose his brother. In Mitsuri's flashback, we can see her persona of an ideal woman of the era destroyed her and made her purposless. Being an hashira is a deliverance to her, not a constraint, it allows her to emancipate from societal norms and to be herself while helping others.

It makes sense BUT I completely agree with the fact that it makes her less huh "legit" than the others hashiras. Compared to the other hashiras, it makes her look kinda goofy that the only reason she's here is because it wasn't fun being normal lmao. It's a way to avoid, once again, the same dead-family backstory but I understand why you'd think it makes her and her motives underwhelming. (Even though it makes sense and it's for more than just "girls stronk too")

The fights scenes are disappointing

My problem with the fights of this season is that I just can't go from mach 20 ahh fights with crazy coregraphy to a very slow burned paced fight where everything is in slow motion.
Through some fights I was just like "Mf you can practically teleport with your speed what are u even doing".
This can be very easily explained, in Rengoku vs Akaza and in Tengen/Tanjiro etc vs Daki/Gyutaro Ufotable could easily add moves and attacks since the structure of the fights were mostly "lots of attacks deflected" or "exchange of many blows". You could have the crazy ideas and execution of Ufotable with the key fights moments of Goutouge's original work. But in S3 the fights structures were so skimpy and strangely complicated yet boring that Ufotable had no place to develop their creativity. They had to follow the exact route or else it wouldn't make sense. The thing is that there's a difference between manga KnY and anime Kny fights. It might work in the manga but as I said, the anime already elevated the fights so such a level, these fights felt stupidly ambitionless and dull. (If anyone is wondering, it's actually no wonder I talk so much about the fights in a nekketsu where the principle is that ALL the conflicts resolutions and peaks of characters will be written through the fights)

No creativity ? No worldbuilding ?

Okay, KnY has never been the CEO of creativity but the pillars powers are simply just inexistant now? Mitsuri litteraly has no special techniques and her attacks aren't related to "love" (well I don't know how that would've worked...). Muichirou's powers are litteraly just wind slashes (ik it's mist). While the emotions demon moon powers were somewhat of a surprise, the "oh no I've cut his neck but he ain't dead" plot twist was already used last season so the core principle of his power was undewhelming. We already had Rui with his threads, Daki with her belts and now we have the multiple dragons. They're all different blood arts but fundamentally they offer the same threats and the same sort of fights. And I'm not even going to talk about the pot demon.

In terms of worldbuilding or rather atmosphere, the entertainment district outclasses the village of this arc by far. I know it's not supposed to be a competition but I felt no attachment to this village and it wasn't immersive enough to make me think of an actual distinctive place. I was fascinated by the entertainement district atmosphere and I was actually interested by how things worked there. I felt like they were in a special and unusual place. We don't even know the specifics of the blacksmith village, we just know it's a bunch of blaskcsmiths put together with an old headmaster. The immerson is just weak.

Was there anything good about this season ?

Yes. The last scene with Muzan was damn cool, as for any Muzan scene tbh. I was actually intrigued and satisifed with his backstory. The Nezuko plot twist was rather interesting especially the scene where Tanjiro's ideals were conflicted. He had the choice between saving innocent people and saving his own sister. I have to admit some scenes like Haganezuka sharpening his blade at any cost were pretty good ideas to make the story entertaining. Even if it's sometimes too much the "let's appreciate each other" and empathical vibes of Demon Slayer is one of it's charm. And of course you gotta give credits to Ufotable's incredible and consistent work as always. They were still some things that were decent to very good about this season but to me the bad aspects overshadowed the good ones whereas it was the contrary for S2.

It still pisses me off how everyone was just happy for Tanjiro when Nezuko could walk under the sun and talk. Like what ? The whole life of demon slayers is devoting themselves to kills demons because their loved ones were killed by these creatures and a random demon just practically became human again and eveyrone is okay with it ? I'd be frustrated as fuck like "so my family actually had a chance", "why her of all demons?". It's the downside of the all lovey dovey atmosphere of Demon Slayer, every character have so much empathy for Tanjiro that I'm certain at some point they'll just become Tanjro groupies. Of course they'll still be distinctive characters but they'll all think and react the same. That makes sense in the story but it can make it particularly unbelievable and annoying. looks like I already stopped talking positive about KnY so I'll move on with this section

Conclusion

Despite it's many weaknesses, the strenght of Demon Slayer is to make it's viewers feel intense emotions. This season was underwhelming in many ways, making it hard to make some viewers like me feel anything. By result, I was only exposed with the many weaknesses of Demon Slayer. There was a nice message and some cool elements here and there but that wasn't enough to justify the disappointment this season was.
Some may wonder why the score is so high despite all the negative critics I made, well, the main reason is that I don't know how to rate it, I havent done so in a long time and there's too much things to consider between the standard of Demon slayer, the specifics of this season, the high and lows and the perfect visuals and musics brung by Ufotable. Most people will probably just look at the score but I hope my arguments will be more remembered than this arbitrary score that means different things for each person. Thanks for reading my review!