The GPU makers support Open GL just fine, since OpenGL maps to hadware feature sets given the proper driver support. On the other hand, for all of its supposed performance, OpenGL is so, well, OPEN that support for even many DX9-class hardware features are nominal and must be authored by the developer.
What yer looking at is a game developer issue -- it probably shipped with a custom version of OpenGL32.dll that wasn't as conformant to the rather well-published MS DLL specification. THat's what you get for playing ghetto games!