Now lots of people start using one particular Matrix instance for that kind of communication.
Now the popular instance stops federating and people can't reach the companies they want to talk to anymore.
The way Google took over was by offering a better user interface than other public XMPP services.
If Google is obviously worse than other Matrix instances, then people will quickly drop them.
Though XMPP had to deal with a number of paradigm shifts: images, markup, audio and video calls, persistant history, disconnected operation, security, threading, multi device operation. And I probably forgot a few.
Today messaging is much more established. So the matrix team has many more examples of features that are in common use and how other people designed user interfaces.
So it may be harder for Google to win through engineering. They may just break other matrix clients on android.