Comment by taspeotis

    API use was shifted in favor of DirectX
    by Microsoft's two-pronged DirectX
    campaign around the launch of XBox
    360 and Windows Vista, including the
    spread of FUD (fear, uncertainty and doubt)
    about the future of OpenGL, and wild
    exaggeration of the merits of DirectX.

I thought it was because that, at the time, the OpenGL API was shit [1].

    By the time of OpenGL 2.1, OpenGL was
    running into a problem. It had a lot of
    legacy cruft. The API wasn't easy to
    use anymore. There were 5 ways to do
    things, and no idea which was the fastest.

And really, the author of the blog post should have known this when the blog post was written...

    By David Rosen on January 8th, 2010

OpenGL 2.1 came out in 2006 [2].

[1] http://programmers.stackexchange.com/a/88055/7067

[2] http://en.wikipedia.org/wiki/OpenGL#OpenGL_2.1