I don't disagree. However, if I understand what Satya Nadella is trying to do with Microsoft, I would expect to see growth in open source Windows targeted software.

For me, I think a reasonable definition of a healthy development platform is one where developers are investing their time and sharing their expertise to develop tools and applications specifically for that platform. Having a windows focused code base for web browsing and all of the components that entails could be an encouraging reef from which open source eco-systems could spring.