They’ve got so many empty spots with more on the horizon that there’s not much point axing stuff early. Stuff is lasting twice as long, yet we’re still on track to get the regular ~13-14 new series, which essentially means we have twice as many free spots as a few years ago. There’s no competition between series anymore, just whether something can find even a smidgen of an audience on it’s own. Rather than cancelling at 2 volumes, they’re better off waiting another 2 and seeing if anything pulls a Kimetsu/Act-age I suppose.