That's quite informative. Thank you. What is still confusing though, as an end user if I can participate anywhere from any server, I'm not sure what things to consider before picking a server. It doesn't seem to really matter, does it?
If you're on an instance with a reputation for lax moderation or the other hosts don't like your politics you won't be visible to users on those other hosts. There's a naughty list of hosts that allow free speech or are a home for feminists for example.
