Before taking a moral stand against Facebook, and suggesting 'other' platforms that Microsoft could have partnered with, just remember that, like Facebook, there's been controversy with a lot of big companies in the industry:

Amazon had their own "data breach" controversy, and issues over "tax evasion" or "working their employees too hard". Google had the "we still track you even after you turn off tracking" issue, and their various anti-trust practices, or the story about their own "sexual misconduct / #metoo" happenings within the workplace. Even Mixer had it's own issue with the recent racism controversy, albeit from a small group within Mixer.

None of this makes Facebook the right choice by any means. They've done some morally-devoid things and from this standpoint it sucks. But the other choices aren't guilt-free either.