So right now the fediverse is still pretty small and although there is one really large sort of flagship Mastodon server Mastodon.social, most of the fediverse runs on really small servers, a lot of single user servers, a lot of really little ones with a dozen accounts or a few dozen. If you are on a server and the server team or perhaps just the individual running your server gets into a fight with someone who's running another server and cuts the connections between your two servers, that can obviously feel unfair and upsetting and then you have to move to talk to your old friends again.