Well OpenGL runs on MAC, Windows, Linux, Solaris, MOBILE PHONES!
You name it and it can run OpenGL. It is not about the OS it is about "shutting" you out if you don't use Windows. Games should be free of those boundaries.
There's more to the life of a developer than access to OpenGL. Its all about access at API level and the functions it provides, together with a host of practical development tools, compilers yaddi yadda, needed to write and package the whole thing. The latter are not going to get written for other platforms in the same quantity and quality as for the Windows platform, unless there is a known and proven business case for doing it.
So why should a developer struggle through another platform if the tools are not there; and even if they are, why do it if the user base for that platform is relatively small? With the growth of Linux use, no doubt in the end the needed tools to make life easier will be written. Not at this moment in time though, I am not surprised they dont exist in quantity, Companies are not charities, grand theory is one thing, reality is another, they have to make a profit, else kiss goodbye to any games at all.
Only a lunatic releases a book written in Mandarin expecting it to be a worldwide best seller.
Regards
Zy