As far as I understand, there are simply more of them coming from kbin, not most of them.

I was speaking more about instances that are specifically made to host such users or encourage such behaviour.

I think that defederating should be left as a last-resort option. The more instances we have in Lemmy communicating between each other, the better (unless Nazis/bigots/etc).

Depends on how much bigotry and spam comes from this instance.