That said, I've succeeded in gradually getting some of my friends onto Riot/Matrix. To be clear, I did it without much technical/ideological evangelizing or being obtuse, just on the basis of them wanting to talk to me and in our social group. But Riot is also at least nice-looking, multiplatform, has modern features etc. Things that are still annoying:
1. Dealing with Riot/Matrix system/client confusion. Most people don't care about such distinctions, I should probably just focus on talking about Riot. (I understand that developers may choose to do different in their communication)
2. Entering into 1/1 conversations. I still don't know/remember how to reliably do it with a new person, always did it by trial and error by trying to invite in ways X and Y etc. It probably requires finding the opt-in into email invitations in the configuration by each participant. I understand these are some anti-stalking measures, but God is it annoying.