Wikipedia is not a good source on this. By the time Google's XMPP based messaging product was renamed "Google Talk" it had long ceased to be compatible with the wider Jabber federation.
While I agree that Google does also sabotage their own messengers, it was deeply involved in XMPP specs development and other stuff around the ecosystem in the beginning, and then just quietly began to blockage urgently needed changes as they were unwilling to implement them in their system.
But I guess this discussion has reached the end of being useful as you clearly have a lack of understanding what actually happened back then.