I've got nothing against well written child-characters. My favorite anime of all times is Fantastic Children.

Kimetsu looks like another case 'kids have it all figured out, adults suck' and I'm too tired of that shit. I don't want to watch kids fight dramatic battles, speak philosophical trite and sacrifice themselves because they're oh-so true to their mission. :/

HXH is a fantasy setting AND has plenty of capable adults, too. Not comparable to Kimetsu's pseudo-realistic samurai setting.