Crouching states work differently in the 3D genre than what 2D players are likely used to. When crouching, you not only get access to new moves, but you also get a completely different set of moves while you’re rising from the crouching to standing state. On top of that, there’s various ways to cancel the crouching state, and those methods tend to differ a little bit between different 3D fighters.
Because of this, there are lots of punishment opportunities that slip right by new 3D players. There are many different types of moves that force you into a crouching state on block or hit, which limits what you can do afterwards. That does not mean these moves are safe, though — and if you know your character’s options from crouch, you can make better decisions as you encounter new forced crouch situations.
Source: Scallywag 93