With these components, you can host your own messaging platform.
Naturally, if you're making a new channel for a group, you have to ask everyone in the group to join it. That's the case whatever messenger you use.
There is crypto now for private messages, but it is a little clunky to setup still. I hope that the funding helps make this better!
For friends I've shared keys with, it works really well. Of course, right now people will only join for ideological reasons. That's OK though!
I also invited some friends to join my Matrix server directly, but there wasn't much pickup yet. But that doesn't matter since I'm already connected to the places where people are via Matrix.