It all depends on your playstyle, 41212 can be used for possession or counters, but because you don't have wingers in that formation, you still need a lot of passing through the middle to get to the opponents goal, while with 433 if you have fast build up with "8 players inside the box" on offense, as soon as you recover the ball in front of your box wingers are ready for counter, and then you can just run in straight line to the corner flag

I mean people can play with any formation they like, i'm just saying that at some point 433 stops being effective, same as 41212, you always need backup plan

I'm using 41212/4222/4231...

with 41212 i dominate the match, get the most chances and usually score at least 3 goals per match, and i'm the one getting counter attacked by opponents, my depth is 6...

But when i can't break down someone's defense i switch to 4222 because you then have 2 strikers and 2 players who are basically like wingers