There's such a deep seeded, systemic bias against linux that it actually can never win, to any degree or magnitude, because the moment it starts winning we just move the goal-posts for the flimsiest of reasons to ensure it can't quite claim that victory.
Linux is obviously and clearly the most popular operating system kernel on the planet. Oh, no, that's no good a measure, servers are messy, let's refine it to most popular consumer operating system kernel? Oh... it, could also reasonably claim that title? No no, no Android, that doesn't count. Nope, No Chrome OS either, you can't have that, that's, well, that is linux, but its not. Just nice, pure, desktop linux, yes, perfect, arch linux, kde desktop, that'll never trend up and thus is the perfect new-new definition of desktop linu--wait hold up, I'm getting word this is, not possible, its actually SteamOS? Nope, kill it, that's not desktop linux either, kill it.
SteamOS solved the chicken-and-egg problem and is demonstrating that Linux-based gaming is viable. 2% isn't a massive number, but it might just be enough for a game developer to justify compiling a Linux-native version too.