They still do. I communicate through Bitlbee/libpurple's XMPP client with friends on Google Hangouts (or whatever it is called now).
https://eion.robbmob.com/blog/2009/11/04/xmpp-facebook-chat/
Supposedly WhatsApp is also based on xmpp:
https://en.wikipedia.org/wiki/WhatsApp
It is a great pity that something that has created so much value for so many companies now somewhat languishes. A real shame. Not that xmpp isn't great, but it'd be so much better if the platforms that benefited from it had only contributed back more.