Having said that, is the UI/UX apart from the above really terrible? When using as a simple messenger app, the experience for me is almost the same as WhatsApp (which almost completely replaced sms at least in the Netherlands). The biggest issue I have is that when you open the emoji selection screen when typing a message, you have to close this and reopen the keyboard to continue typing, which is a bit silly, but not a deal breaker.
That's exactly what I like about Matrix. I can verify other devices simply by comparing emojis - simple, easy, great. That it should work reliably is a completely different matter, but in itself it's great.
In my experience, neglecting the onboarding experience is a cardinal sin for any project challenging some incumbent.
I‘ve been struggling with understanding what Element wants from me when signing up or signing in on a new device. Unfortunately I can‘t, in good conscience, recommend this to less technically knowledgeable friends and family.
...Except you can? federation_domain_whitelist in synapse settings. Seems to have been working since 2018. I'm using it. Enabling it can sometimes cause significant delays when communicating with users on homeservers you're not federating with, though - I have some vague memory of seeing an open issue around improving relaying in these scenarios.
I do agree that there's a long way to go before I can start recommending anything Matrix-based for friends and family. Things are just too slow, broken and inconsistent on both server- and client sides. There has been steady progress on all fronts, though. Maybe in a year or two.