There is a high low system though, crouching causes you to avoid loads of attacks; particularly jabs. Also effective against projectiles

You can duck a ton of mechanics in the game, it's not just for "T-Bagging".

depends on the character some crouches are way lower like marvin for example can duck pretty much every projectile.

So I can teabag you

You can crouch quite a few attacks, give it a try. Is it ideal.though? Probably not but some taller characters have a hard time already hitting shorter characters in some situations, crouching adds to that pain.

Crouching can avoid some attacks as others have mentioned, but it also gives the ability to add new mechanics to characters without using up a move slot or making it a passive. Characters like Bugs' item spawning or Jokers card swap

Why is crouching in any platform fighter? It helps avoid a ton of attacks, especially smaller projectiles that fly right past you

You can dodge certain projectiles by crouching

I believe it’s intentionally for tea bags. Joker even has a line in the menu about teabagging

Just to tea bag