Sifu is super guilty of this: The good ending requires you to not kill any of the bosses.
Let me emphasize that:
THE BOSSES.
The hundreds of hapless mooks standing between you and the bosses? Kill the hell out of them, they mean nothing.
But oooh, you’d better not kill the final boss who happens to be your older brother who stabbed your order in the back, or else your dad is gonna be disappointed in you from beyond the grave because [something something kung fu philosophizing].
You don’t exactly have non-lethal takedown options for the grunts, either, you either pummel them to death or (if you have a sharp object) shank them to death. Once again, only the boss fights have non-lethal takedowns, and from what I’ve seen of gameplay footage (I’m pretty bad at the game, myself), those can go by so fast that you don’t even realize they’ve happened until you’ve already shoved a repentant assassin’s own knife in her sternum because you were so focused on her not stabbing you that you missed a vital input.
(I just realized I may have quoted the wrong comment, my bad y’all.)