The user need to be conscient of that. Otherwise its really unfair. If he doesnβt know the server he choose did that, he will be restrain without being aware of this.
And in an other hand, if I have to check why someone donβt respond to me (example), to be sure where this someone is, is federated, that would be really painful and discouraging. That can lead to a lot of misunderstood too.