Microsoft has a business to run, like anyone, which is why features like Play Anywhere only work if you purchased games on the Microsoft/Xbox stores, but it isn't fair to hold it against them that they aren't submissively accommodating to their prime competitor, especially when that competitor doesn't play nicely with anyone, really. Sony and Nintendo are the torchbearers of the walled-garden model. Microsoft is accomodating Windows itself which is a semi-open source ecosystem. They've also been working with Steam and others, as you've been shown, who are champions of Linux, which is a pure open-source platform. For the same reason you won't see Microsoft-published games on Stadia (the service, Google, and the Vulkan API are all competitors).
Easily the biggest and most biased fanboy on our board. Watch him try to wax about how he owns an Xbox One X to prove he isn't.
The tryhard fanboy.