I’m old enough to remember when Facebook Messenger was compatible with XMPP (as was Google Hangouts, then called Talk). You could talk to people on there from your own server, you could use whatever open source client you wanted. It was great.

Then they cut off the federation. Then they cut off the API.

They’ll do the same again. Once enough of your friends and family are on their network they cut of federation and you have to move to them if you don’t want to get cut off with it.