XMPP these days often gets used as a friends-and-family style messenger (Think WhatsApp, iMessage, Signal replacement) rather than something communities would use (Discord/IRC). A lot of users of XMPP are also out of the public eye. NATO, police forces and intelligence agencies use it. The community style channels are supported though and a search engine for them can be found here: https://search.jabber.network/channels/1

Yeah, I use it as a messenger for my wife and I.