It was probably born out of the fact that this is the truth for PC gaming, where Microsoft uses DirectX and "all" the other platforms use OpenGL.
For a long time, console game development was obscure and unaccessible (and to a large extent, this is still the case), so aspiring game developers had somewhat of a tunnel vision when it came to game platforms.
I said large scale, not very many people had the accelerators required to use these APIs. Glide is perhaps the first real example to hit a scale that mattered.
