This kind of discussion is where my passion lies...

Shounen power scaling... truly a mysterious art that is required to harmonize with the tone, scope, and theme of a shounen for it to dare step into the pantheon of great shounen anime.

As I see it, there are four important factors in long for conflict/battle driven manga to present interesting progression and conflict: Properly paced strength scaling, Revelation of Scope, power interactions, and poignant power revelations.

Being long form stories, shounen has a very real 'power ceiling' that, once passed, just becomes boring, ala DragonBall. If the numbers just keep increasing but the basic 'gameplay' doesn't change, fights stagnate with simply bigger explosions. Kimetsu is somewhat average in this department, as recent shounen have moved away from flat numeric systems to represent power and typically favor more general rankings based systems. The hashira are understandably impressive, but revealing their prowess this early sets a soft limiter on how impressive the other nine ranks can be while maintaining continuity. The same goes for the other 12 high class demons, however they are easier to retrofit into being stronger or weaker as needed by the story conceits thus far. This creates some burden on the author if they plan to explore the other ranks, as viewers (especially young WSJ readers) are ill equipped to tell apart a very nuanced differentiation of power levels like this, meaning more exposition will be necessary down the line.

This battle also served to set some scope. This is actually the most difficult one to get wrong (which is why I am the most harsh critically of Fairy Tale - because it screwed this up royally) among shounens. Giving the audience a taste of coming distractions and where the hero is headed is great for re-invigorating hype; especially earlier in a series. Again though, the author played his big cards very early, and while this can work (Mihawk in One Piece), it still created a storytelling burden where future characters will likely be compared to the heights of what we have experienced, and that reduces their potential impact on the audience. We've seen the best, so what else could impress us aside from the final villain? From what I hear, Bleach suffered from this as well. Did the author do this as a desperation move to preserve rankings in WSJ, or are they planning on a shorter tale that doesn't need to 'save' high rank character reveals until later? They are a precious limited resource to a WSJ mangaka, so I expect it is more the former...

The power interactions were a mixed bag. On the one hand, modern shounen has largely attempted to sidestep generic 'strength' in determining battles and has taken a page from Jojo in having more clever application of powers deciding battles versus 'strength versus strength'. The split I would guess to be around 50/50. That was largely missing from this battle tactically, but represented fairly well in the animation and choreography, so I don't have any real complaints. Series like Shoukugeki no Souma are entirely built on this, as well as most sports shounen. My Hero Academia also emphasizes this, as well as HxH, and arguably the best (early) portions of Naruto.

The power reveal and relation is the only strong criticism I have for this fight. Like I said, the foreshadowing was paltry (mid-fight flashback) and the power up felt unnecessary, especially since he was saved by the Hashira anyway. It was flashy and exciting, but it didn't have the emotional impact that the best kinds of battles do. For a demonstration of this done right, I would suggest the original Dempsey Roll reveal in Hajime no Ippo. To be fair, Kimetsu didn't have (or take) the time to build this up as much before springing it on us.

Some of these 'compromises' might be due to the compacted format this show has been produced in. UFOtable isn't a long running show producer, so they may be trying to cram in as much source material as possible into its run, showcasing instead its beautiful animation. Still a solid watch, though.