the thing is a build plate is not a structure.

So when you adjust one point it also effect the other 2.
Whe you adjust an edge on a four point plate, you adjust the bolts for just that side.
were you dealing with a tringular plate or a round one as on a delta. it makes sense. Because essentially you are adjusting a trinagle.

But 3 point levelling on a four corner bed is just stupid and almost impossible to visualise and adjust correctly.