That worked out very well on Windows with DirectX. The engines clearly provided an equal experience for both OpenGL and DirectX, not favoring the platform specific API at all.
True, but as with advanced rendering techniques, not everyone wants to use off-the-shelf engines. In a simple application, there's something to be said for writing your own, simple graphics code.
Contrary to FOSS beliefs, consoles never had proper OpenGL support anyway, so game studios already had to take care of multiple APIs on their engines.