MS doesn't like competition.
Even with itself? You do realize of course that there are far more people using PC/laptops that use MS' own OS than there are console users. So wouldn't it be in their own interests to see that people play PC games? As it stands there's less and less reason for people to keep using MS' OS', particulary each new generation - which is more and more redundant and anyone wanting a cheap OS solely for practical purposes are better served with Linux or going to a Mac.
By not supporting gaming on the PC MS is shooting itself in the foot needlessly.
"You have enemies? Good. That means you’ve stood up for something, sometime in your life."