no, just no. you dont get to get out of tight spaces, when enemy corners you, you are dead. when you shield bash, you: A: flinch them a bit and you will get into same situation B: you get hit as soon as you press V OR their team mate, which is pretty common in siege, kills you as soon as you press V.
You obviously are still new to the game. Your assumptions are wild and your logic is incredibly silly.
As a shielder, I have been put in many situations where I was in a tight spot against more than one player and survived. Sometimes I even beat them all back.
Just because
You are not able to do it, does not mean it is impossible.
I can agree that it can be hard to land a shield bash against an experience player. Although that is what practice does. It makes you better.
Play the game more before getting rash about something you obviously do not have enough experience doing.
EDIT: Back on topic. The only thing I will agree with shield bash is the delay after getting hit by an attack. That can be rather annoying. Although, that has to do with animations.