> Matrix is mostly the text chat part, it doesn't implement voice chats or anything.

It's in progress. Keywords: MatrixRTC, Element Call

https://matrix.org/blog/2024/10/29/matrix-2.0-is-here/#3-nat...

Does it have persistent voice channels with simple app/game streaming for free?

fwiw, Matrix has had video rooms since 2022: https://element.io/blog/drop-in-drop-out-chats-with-video-ro... - and VoIP calling since day one in 2014.

I've never used it but Matrix does seem to support conference calls, if not natively then via Jitsi. I'm sure a good app can paper over the differences to get a voice-chanel out of it if this is what people are after, though I've never really used this much on Discord.

The same can be said of space-room vs server-channel. Of course a space has different semantics, the space doesn't own the rooms, etc. But they can be made to be nearly the same for an end user. In general organization of resources is much looser and less opinionated on Matrix. But an opinionated app can also paper over this to force a stricter hierarchy, while offering advanced users the ability to make their own spaces, etc.

If it only works per-client, then it almost doesn't exist. That's one of Discord's strengths.