Yes I'm all for going after Google for different things. And was definitely a big fan when they implemented it into Google talk. But I think it's importance was definitely overplayed.

An in-law of mine wrote a commercial email consolation web service about a decade ago. Which he eventually sold off or a smart chunk of money. But he implemented an on-site instant messaging capability using XMPP. It was never broadly advertised as such. But you could absolutely connect to it through an XMPP client outside the website. But unfortunately not many of the actual users cared about that beyond the fact that it works for them. However I would not be surprised if many of these customer service on site chat applications etc don't use some level of XMPP. We're just not advertised about it.

I believe XMPP today is an IETF standard. Which anyone can and probably do implement. I remember reading about it having integration with SIP servers etc. unfortunately though it was never one of those sexy exciting things that people really look for. It's why Mastodon etc I haven't really blown up but are still chugging along. Most people only care that the people they want to talk to are there and able to be talked to. Not about how it happens in the background or even what they have to give in exchange for it. And I honestly think it is one of the reasons that Lemmy might actually stand a chance. Reddit by its nature was often rather techy and involved. Growing communities is much different than growing personal walled gardens. And if money does a good job of appealing to those community maintainers. I could see general chatters eventually following. Because no one wants to waste time screaming into an unmoderated void.