Having watched MSFT slowly chip away at their traditional bread-and-butter OS model with things like OneDrive and Office in the browser, Azure and then WSL, and listening to the Acquired podcast episodes on Microsoft, I wonder why they haven't simply released a Microsoft Linux by now, if only out of pride?
Do they feel that by doing so they're broadcasting that they're no longer a computing philosophy leader, and merely a market preference fulfiller (which is itself a backhanded way of saying they meet market demand I guess).
To answer all the comments in this thread at once, and this is my personal opinion, building a distro is easy, releasing a distro and supporting customers that use it is much harder.
Ask a very simple question: how would this generate profits, which high level manager would be motivated to do this? Sure, 15-20 years ago corporations would've made vanity/critics-industry appeasing projects like this out of pride alone. Those times are over.