I think their policies have more to do with support costs than anything else. As much as I love playing on Linux and wine, you have to admit there are more technical issues with Linux. People who have low tolerance for glitches and problem solving to get their games working would be up in arms. The last example is Hyper Light Drifter. No matter which forum, the latest threads include several about Linux specific problems. And that's a game with native support.

Another game I played recently - an ancient puzzle game "Riven" - seemed to have bad looking problems. I bought it from GOG because I didn't notice it only officially supports Windows and Mac. Very near the end of the installation, you have to click through a couple of errors that say the game didn't install properly (it did well enough). When launching the game, you get a nasty error if you run Riven.exe instead of Launcher_Riven.exe . During the actual gameplay, there is only one rare crash every few hundred attempts at brute forcing one particular puzzle.