You are being very naive at best. There is at least a couple of problems with current Microsoft:

1) Windows is still closed source, their OpenDocument support is broken, and Secure Boot gives them an amount of power incomparable to anyone else in the industry: https://nudgedelastic.band/2016/01/i-am-still-not-buying-the...

2) DirectX 12 is Windows Store exclusive and it will never be possible to use DX12 apps on e.g. Wine: https://www.theguardian.com/technology/2016/mar/04/microsoft...

3) Patents: http://www.infoworld.com/article/3042699/open-source-tools/m... http://www.infoworld.com/article/2841412/open-source-softwar... https://news.ycombinator.com/item?id=13890580

Of course, all of these things are legal.