That is an exaggeration, and I do not see what is the bad thing about many of the games being written in Unity either.
Crusader Kings 2 and Europa Universalis 4 run on Paradox's internal game engine which was ported to Linux due to Steam. I believe the same is also true for Serious Sam 3 from Croteam. And there is 4A Games who are making Metro: Last Light with their own game engine. I do not think Football manager 2014 will be using an engine like Unity either, but I do not play sports management games.
Yeah, "source" games run on Unity, maybe? That's a good chunk of all the AAA titles available on Steam for Linux currently, and they run great on Linux.
Besides, I have no headache with my Linux systems. I have no idea what you are talking about.
Nothing wrong with that, the more such games the better, but it just speaks volumes to the fact that Linux is as fringe on the desktop as it ever was.
Frankly, I don't understand why gamers who happen to use Linux and who love video games as well don't spend $500 on a Windows laptop and save themselves all these headaches.