Slack is lying when they say XMPP can't support the features they're adding. I've written a blog post about this: https://opkode.com/blog/slacks-bait-and-switch/
@jcbrand What but companies wouldn't lie! /S
@jcbrand maybe they didn't know it was possible, or didn't bother to check?
@jcbrandSee also, Signal.