to be fair, Microsoft has been loosening up on exclusives as of late. Minecraft is supported on all platforms, with the dungeon side game coming to all consoles. Psychonauts 2 is still slated to come to PS4 and Switch. Ori's 2 games are multiplat (the sequel just now releasing on Switch).

I don't doubt there will be timed exclusives, but at the current moment it seems like they aren't opposed to publishing on non-MS platforms.