Microsoft supported OpenGL prior to developing Direct3D. As soon as that got into good enough shape to supplant OpenGL, OpenGL got dropped.

These days you're better off using OpenGL via ANGLE, built on top of Direct3D. That will probably also happen analogously on Apple's platform with Metal, so I don't quite get the kvetching about Apple deprecating OpenGL.

As if it matters whether Apple ships an OpenGL implementation as part of the OS or purely as a normal user space library.