Their customers have few alternatives, and there's no future Windows versions, so Microsoft don't have to play fair.
More so if you view them as a company that is normally less hostile (these days). Though I suspect these decisions are being made by a separate silo from the developer-friendly "new Microsoft" groups.
Anybody that thinks that fragmentation will ever go away needs to spend some time in the real world, which doesn't conform to a nice and simple abstraction.
Businesses get a special deal, they get to use the “current build for business”. But the future of Windows is like the versioning of Firefox and Chrome, not Internet Explorer.
My theory is there's some internal incentive system set up, and the users suffer the ugly consequence of it. Am sure some people bonuses over there depend on quarterly user conversion rates.