I use them regularly, and switching to another software is a hurdle I would like to avoid. Also I am not happy with existing software (Teams etc.).

XMPP works, but there are no video calls. Matrix has those, and they are very good. But since it is not possible there to see the online state of my friends (turned off everywhere due to horrible performance), it defeats the purpose. I want to see if they are at their computer, not if they own a mobile phone. 😉