Really very similar to Lemmy, where the identity of each group is tied to a particular server, e.g. lemmy has !anime@ani.social but Matrix has #anime:matrix.org

So what happens if matrix.org goes away or decides the server admin wants to be hostile to #anime?

A matrix room can have multiple identities/adresses set by the room admin. E.g. the admin of !anime:matrix.org could add another adress for the same room on !anime:myanime.instance. Because the room is replicated on all other participating servers, this would let the room continue to exist on the network (besides all matrix.org users not being able to access it).

Matrix does have a single "room id" per room, which looks like it gives the original creating home server more rights, which it does not. E.g. !ehXvUhWNASUkSLvAGP:matrix.org

Any server admin does not have any more rights over a room than another server admin. They can ban the room for their local users, but this does not stop federation as a whole.

[1] https://github.com/element-hq/element-meta/issues/419
[2] https://app.element.io/#/room/#synapse:matrix.org/$htJmba92wLTP9AoFg4eEWi9IXpgwvXr6G9Sa-kBsNNs
[3] https://matrix-org.github.io/synapse/latest/admin_api/rooms.html#delete-room-api

It also appears that anything beyond text has to be hotlinked [...]

Matrix allows for media to be hotlinked, but it can also be replicated across servers.

I.e. if I send an image in a room and look at the source (available on many web clients), the image url looks like the following "url": "mxc://matrix.org/qGgUKuZuHcRsWAhSfqKnmtiX". The actual image (and preview) then gets fetched by your server from my server [4], and then gets send to your client.

It's important to note that a server isn't required to download all media. If a user does not read a room, it might not download the media from another server, until the user actually wants to view it (or rather that part of the room history). Or a server admin might clean up the media store to free up space.

[4] https://matrix.org/docs/spec-guides/authed-media-servers/

@JackbyDev@programming.dev