The thing is, OSX is technically a better gaming OS than Windows - it has many advanced built-in and tightly integrated features and uses OpenGL for ALL of the graphics.
But the problem is, Win is much more widespread, so game developers release/optimize their games only for Win, leaving OSX with all its advancness unnoticed.
That is debatable. DirectX is in some aspects a better API than OpenGL and OpenGL tight integration in the OS causes stability but it does cause some overhead (I remember reading this from a Mac developer, wish I had a link), hence why even equally optimized games (like Blizzard's) still perform worse on Mac OS X.
Even so, the whole point is that Windows is the better gaming platform, potential means nothing because we all know Apple apparently hates games.