I didn't say it was easy :) I think you could sign up across a set of servers, whoever is willing to put their server in the list. But you are correct, there are a host of issues, since it's all decentralized. That's the cost of decentralization, but there are solutions. One would be to be put on the list your SLA/privacy policies/etc must meet some min. standards(1) exist 2) be found at a .well-known/ etc. that way the client can easily show them to the curious user.

The problem with just a username, is that's not what you need to converse with ANYONE in XMPP land, you need the full XMPP address, and last I checked, no client makes that easy for you to figure out. The full XMPP address should be easy to find as that's what you actually need. Just a username doesn't work, give up on only a username being all you need, it isn't.

I think doing invites from a tech savvy snikket server instance makes sense FOR THAT USE CASE.

For Tito's Grandma, where Tito & Grandma are not tech savvy people.. that's not easy. Tito gets setup on server Y and Grandma gets setup on server Z, and neither of them can talk to each other because the client only shows the 'username'.

Again, I haven't knowingly used Snikket, but last time I played in XMPP, it was non-trivial, even for a tech savvy person.