>>281577602
It was a way of accomplishing several things without fucking up the powerlevel logic.

>Tanjiro and Muzan's first and only conversation while completely alone
>Muzan admiting his loss to Kagaya and reinforcing the story's main theme
>Nezuko and Tanjiro "defeating" Muzan as a callback to Tanjiro's declaration in the first Pillar Meeting
>Shinobu accomplishing Kanae's dream of forging a bond with a demon (Tamayo)
>payoff for the "if I ever become a demon" scene during the Gyuutaro/Daki fight
>Inosuke's final piece of development when the fightfag facade finally crumbles
>giving Nezuko a big emotional scene at the end that works as a callback to the 1st episode, since involving her into the fight itself would be an automatic gameover.

>>280825766
>after an entire night of just trying to survive, muzan is exhausted
>dawn is breaking, his skin is burning, the obsessed ubuyashiki fanatics have him surrounded
>suddenly
>an inherited memory, the doctor he killed 1000 years ago appears to him
>he tells muzan where the blue spider lily is, and that he must live to pass on his legacy as the best doctor of all time
>muzan finds the inner strength to kill tanjirou, escape underground, become perfect, and live happily forever after with his friends