The problem is more that they're holding several large bona fide communities hostage this way. For example !linux@lemmy.ml is by far the most active Linux community on Lemmy, and because of network effect it's not easy to get people to move to another instance.
It would take something huge to get people to move, for example some of the larger instances like lemmy.world defederating lemmy.ml.
No they don't. I received a two week ban in the wake of the API protests, never got an explanation why or what comment triggered it.