It's honestly surprising that people still continue to insist that anyone but Google is responsible for the current state of affairs. It's completely because of Google's business incentives. Google's pivot, from a Blackberry clone to an iPhone clone, was about quickly obtaining market share. That meant ceding control to OEMs and carriers so they could effectively market devices against the iPhone.

Microsoft didn't lose because of those things (it shows how much better they are at being a platform company that they didn't repeat Google's mistakes), they lost solely because Android was free to OEMs. That's entirely a business model question.