They left because they lost all trust

David Sobeski was a General Manager with Microsoft. 
He posted about "what went wrong" https://www.facebook.com/dsobeski/posts/10153683440480008

"The trust with developers has been a long deteriorating problem. .... Then, everything went to **** when .NET was released. Changes were being made to the C language, to the Visual Basic language. In one fell swoop, Microsoft told all of its developers that everything they were doing and did was wrong. Stop all that crazy C code or the AddRef / Release or that insane VB or Access code and use the new new thing."

"Being a developer for a Microsoft platform was insane. Don't forget Office. One of the largest platforms on the planet. It avoided all this and you still used VBA. Office had to continue to use VBA because there was no guarantee of compatibility between VBA and VB.NET. But now you were an island."

"The Windows Phone team did something that would seal its fate forever and lose the trust of developers. Windows Phone 7 was released with a new user experience and was the answer to iOS and Android. It actually got developers excited. But, a year later with Windows Phone 8, Microsoft told all the developers that the investments they made in Windows Phone was a waste of time because none of their apps will work on Windows Phone 8. That was it. It was over."

Sobeski concludes: "At the end of the day, developers walked away from Microsoft not because they missed a platform paradigm shift. They left because they lost all trust. You wanted to go somewhere to have your code investments work and continue to work."

by Chucky1