Windows generally has less of an issue of heterogeneous graphics driver ecosystem, mostly for market reasons---Windows laptops and desktops are bought more often for the purpose of playing games than Linux machines, so a Windows machine hitting the market with a graphics driver that's too outside the norm tends to perform poorly in sales, and the market encourages driver homogeneity in basic functionality. I've seen some stinkers trying to write my own game engine (THANKS FOR LYING ABOUT THE OPENGL CAPABILITIES BY IMPLEMENTING IT IN SOFTWARE AT SECONDS-PER-FRAME PERFORMANCE, INTEL, YOU ARE A PEACH), but not as many as in Linux.

(in short, "What machine should I buy to play games" is a question that's easy to answer for Windows; there's reams of magazines dedicated to the question. It's a harder question to answer for Linux, which makes it a harder question to answer for developers trying to write games against a Linux-based OS).