FWIW OpenGL only mapped to how the hardware worked for a particular vendor (Nvidia) and a very short time (~GeForce 2, IIRC).

OpenGL was always a higher level API, it just is an API that provides functionality instead of being a framework (so you had to make your own). Even in SGI hardware a lot of features were done only in software and during that time on PCs most cards could barely do more than rasterization and transformations (and some not even that).