I think its not only the clients...Rather its what the server side supports and to ensure clients align with that....And i think among a group of techy friends, well, they can coordinate the proper settings...but it becomes thorny when involving some not-techie buddies...Of course its possible, but, you know, the onboarding process is less than ideal. I say that not being an xmpp guru of coruse, so YMMV.

> I am really surprised there isn't a venture backed company pushing XMPP forward. Maybe people have tried and realized it's not viable.

Actually, WhatsApp would fulfill your definition there. They are/were a startup whose entire product/platform is an xmpp client (using their centralized server/instance). Now, whether they pushed "xmpp forward", or merely would be considered pushing a chat platform and who cares whats under the covers...well, that i leave as an exercise for you or others to decide/opine. ;-)