Google dropping support for XMPP is what put it one foot in the grave. They abused the protocol to gain the lion’s share of users for Google Talk, and then cut off any resistance that remained. It exists still, technically, but when’s the last time you heard about or used it? I only know about it because EVE Online players used it for large group text communication before Discord became a thing.
XMPP still exists in the same way that critically endangered animals still exist: barely and by the adamant will of some dedicated few.
It certainly doesn’t subtract from the experience, that’s for sure.