Yeah, of course it would have not ever been a mainstream thing for end users. But Google definitely nipped them in the bud, both by providing a (bogus) drive behind the XMPP development (and so, preventing anyone else from doing so), and also by kickstarting them into relative widespread use instead of letting them grow organically.

If they had, there is a possibility XMPP would have become a service provided by nerds for their friends and family as soon as 2010, like email, or more recently, nextcloud.

And it would have been a valid option for corporate solutions. But no, instead, we got slack. Thanks, Google.