> The other thing is they all want to take over the entire domain you use them on
That's not true. Many such projects use /.well-known/ to provide the ability to redirect from the root example.com identity to where you should actually go to send things.
Could you source that? I'm not saying it's incorrect I've just not come across it in these things yet. That'd be the key to getting me on the decentralised bandwagon
Matrix doesn't take over the whole domain; right now you use an SRV record to point to the right place and we're planning to switch to .well-known URLs. source: i work on Matrix.
As an aside, what is the current status of identities in the matrix fediverse? Last time I checked it seemed like the centralisation of identities was "punted" on and you have an OStatus/WebFinger-like system where identities are tied to a particular server.
NextCloud / ownCloud have federation but the WebDav links are described in /.well-known/. I haven't installed Mastodon so I can't speak to it, but since WebFinger uses /.well-known/ I would be surprised if Mastodon did anything else[1].
That's not true. Many such projects use /.well-known/ to provide the ability to redirect from the root example.com identity to where you should actually go to send things.