It's kinda-sorta social problem, but originally not the way you intend. It used to be possible to self host XMPP and chat with people regardless of the platform since both Google and Facebook (it wasn't Meta at the time) adopted the protocol. But then they changed their policy and created the walled gardens they have now and thus it's a social and/or political problem.
They fully followed the playbook of Embrace-Extend-Extinguish which eleijeep@piefed.social mentioned few messages up the thread and pretty much devastated XMPP out of existence. Sure, there's still handful of users and project itself isn't dead, but before their policy change I saw quite a lot of servers around which are now either dead or forgotten.
On a previous comment I didn't mean to describe that as a technological problem but a problem related to big corporations embracing FOSS projects/protocols and killing them by introducing their own walled garden variant of it.