http://blog.wolfire.com/2010/01/Why-you-should-use-OpenGL-and-not-DirectX schrieb:
Microsoft initiated a fear, uncertainty, and doubt (FUD) campaign against OpenGL around the release of Windows Vista. In 2003, Microsoft left the OpenGL Architecture Review Board -- showing that they no longer had any interest in the future of OpenGL. Then in 2005, they gave presentations at SIGGRAPH (special interest group for graphics) and WinHEC (Windows Hardware Engineering Conference) giving the impression that Windows Vista would remove support for OpenGL except to maintain back-compatibility with XP applications. This version of OpenGL would be layered on top of DirectX as shown here, (from the HEC presentation) causing a dramatic performance hit. This campaign led to panic in the OpenGL community, leading many professional graphics programmers to switch to DirectX.
When Vista was released, it backpedaled on its OpenGL claims, allowing vendors to create fast installable client drivers (ICDs) that restore native OpenGL support. The OpenGL board sent out newsletters proving that OpenGL is still a first-class citizen, and that OpenGL performance on Vista was still at least as fast as Direct3D. Unfortunately for OpenGL, the damage had already been done -- public confidence in OpenGL was badly shaken.