Matrix also keeps your message on the server. Except you can run your own server. And the messages are end to end encrypted. And you can keep a proper backup of the keys.
Granted it can be clunky at times, but the properties are there and decentralised end to end encrypted messaging is quite and incredible thing. (Yes, Matrix nerds, it's not messaging per se it's really state replication, I know :))
As you alluded to, Matrix has really horrible UX. Telegram is meant to be easy for the many to use: finding content in chats or even globally across public channels for example is intuitive and snappy because their server does the heavy lifting. That's a huge sell for many, myself included.
My Matrix messages are, I presume, not encrypted, because every device I have prompts me to sign this device's keys with the keys of another device (which doesn't exist) and the option to reset the encryption keys and lose access to old messages doesn't work either (it just crashes Element).
Ah right. Yeah I keep forgetting that there are other clients beside the ones by Element because none which I initially tried were as fully featured as the Element ones.
Granted it can be clunky at times, but the properties are there and decentralised end to end encrypted messaging is quite and incredible thing. (Yes, Matrix nerds, it's not messaging per se it's really state replication, I know :))