Do you know in what ways they make it difficult for OpenGL programmers? Do they intentionally gimp the OpenGL implementation in Windows?
I wouldn't say that they gimped OpenGL, they have no real way to. What they did do is make parts of Direct3D have access to things in unique ways that OpenGL cannot do due to not having a handbook on WIndows implementations. They then heavily incentivized using Direct3D to game developers.
Also, OpenGL is just a 2D/3D graphics API, whereas DirectX is a whole multimedia and gaming API. It isn't right to compare OpenGL to DirectX. DirectX vs SDL or DirectX vs the Open*L family (though that's a bit of a misnomer since there is no cohesive body of Open*L, just different companies releasing stuff as Open*L to make it clear that it is an open implementation) makes more sense.