Correct.
But in the case of matrix you can host them in your home if you want, or maybe on your phone(they are still checking if this is possible or not)
Maybe I am capable to do so (although I already host an XMPP server, so Matrix is rather redudant) but expecting everyone to self-host is obviously not realistic.
Currently Matrix is operating in a way that larger instances aggregate private messages from bridges in plain text. Those messages would have stayed encrypted and secure if people didn't use Matrix.
> Currently Matrix is operating in a way that larger instances aggregate private messages from bridges in plain text.
That's not true in general. For most if not all messengers (at least encrypted ones), there is the option to use Bridge-to-End encryption on the Matrix side, which doesn't give the homeserver any possibility to inspect messages let alone aggregate them.
If I understand correctly, the Matrix encryption and message format is not compatible to other protocols so all messages must be decrypted and converted on the homeserver which runs the bridge.
The bridge and the home server are separate things.
So if you run the home server somewhere untrusted, but the bridge in your home with E2EE enabled, the decryption AFAIK happens in the bridge, and the home server doesn't see anything.
I doubt many users will host their own bridge. Also at least for XMPP I was not able to encrypt messages to Matrix users end-to-end or bridge-to-end, so I'd still recommend using XMPP with E2EE directly.
