Seems many have forgotten (did not know) that in the earlier days of all three of these Big Tech that they used XMPP to easily lure new users in so that those users could easily maintain contact with any friends outside of their services. Once their numbers had really swelled they each announced shutting down their XMPP capability and at the time as users we did not fully realise the impact as many / most of our friends back then were using Google, Facebook and Microsoft. Little did we know that this wall (loss of XMPP) would create the stickiness to keep most users captive as they would no longer have any easy chat facility with their friends who did not move.
Facebook brought out Messenger, Google Talk became Google Hangouts, and Microsoft pushed users across to Skype. They each decided to build their own walls instead of seeking out ways to maintain interoperability. Imagine today if Gmail could not mail someone on Microsoft Outlook, or someone with a private mail server?
Yes they could have used XMPP as the "X" stands for extensible. XMPP has numerous XEP standards defined for extended functionality for voice, video, files transfer, and much more. Thing was while there was one standard for e-mail, XMPP was never declared THE single standard for messaging. This is what levels the playing fields and allows all services to interoperate.
But Big Tech does not want standards like this and although many governments have declared certain interoperable standards, they really have not enforced them at all. It's us the consumers who suffer as we are walled off from one another and have our choices dictated to us. We need more international open standards declared and as consumers we need to choose services that embrace those open standards. This will lower the cost of doing business too, and make archiving access more resilient to the closure of businesses.
Screenshot below from the Wayback Machine archive as the announcement has long gone from Facebook's dev site dated 2015.