What I like about Matrix so much is that it can be run fully on your own infrastructure, even the TURN server for VOIP, and you can build the clients from source yourself too.

But I agree that it's quite difficult to use. And until now only my dad and my spouse use it with me because they love me and trust me. But they both always have problems with their clients. It randomly logs out and then they have to login with the password and with the encryption key again. For a long time calling didn't work because I misconfigured the server. Then videos were for the longest time uploaded in full size and anything longer than a few seconds would be rejected. The whole spaces thing is implemented very weirdly so it confuses them. And then the threads are even worse so we can't use them because nobody gets how to do it.