Why, because Lord Dave is a noob and software developers aren't perfect?
No, I mean the way he fixed the error in the first place. Linux gaming will only win against Windows gaming if it is easier. Security, cost, and speed are great, and Linux can probably deliver all three to the gaming world, but usability is the #1 thing that increases adoption. If I can't download Steam on Linux, double click an executable, and have it just work, then I won't use it on Linux, and neither will millions of other gamers. What Valve is trying to do is admirable, but until they really get their shit together no one is going to touch their SteamOS or Linux in general. This will ultimately kill Steam on Linux. Valve will either make it easier or abandon the project. This all started because of Gabe's pissing contest with Microsoft and I'm pretty sure it'll end just as quickly.
Linux isn't used by many people the same reason Bitcoin isn't used by many people. It's hard as shit to use and anyone who doesn't actually need the functions it provides would never use it.