Does EA even have any games on Game Pass? They have their own service. Ubisoft also has their own on PC, which is why all Ubisoft GP games have been console only (although Microsoft Store's heavy limitations may also affect things).MS, Ubi and EA all seem pretty happy with it.
I expect other pubs to follow if they have a big enough game library.
Big publishers are going to exit GP and make their own service when it makes sense for them.