It should be noted that Mastodon is in process of adding e2e encryption. And Matrix chat has implemented the ability for server admins (at least on synapse server) to enable e2e encryption by default for all rooms.
Even still, as long as accounts belong to specific servers, the relationship of user to server admin is still a little too close for comfort imo. Perhaps a simple business relationship of "you pay me and I host you" would help here.
Agreed. In matrix/synapse, even with e2e enabled the server gets a ton of metadata, including presence info. Also the identity server exposes quite a bit.
Even still, as long as accounts belong to specific servers, the relationship of user to server admin is still a little too close for comfort imo. Perhaps a simple business relationship of "you pay me and I host you" would help here.