In a lot of ways, it's just that clash of what happened when two big PC genres (FPS and RPG) started switching over to consoles. PC gamers are justifiably annoyed that they're becoming an after-thought and bemoaning the various ways the games have been changed for the console.
I hesitate to use the term "dumbing down", but when auto-aim schemes returned (after being phased out shortly after mouselook was introduced), you have that really easy in to point out how much better these games used to be.
And I think you also have some of that console rivalry in there as well. Console fans have long been taking pot-shots at one another, then suddenly come these PC gamers, already annoyed that their favorite genres are being altered for the console crowd, who know have to deal with people who naturally talk smack about each other systems and not taking it in the proper spirit. Their response is to provide a long list of ways in which PC gaming is superior, which has the bad fortune of being mostly right (PCs are capable of better graphics and the keyboard/mouse control scheme is extremely good for RPGs and FPSs).
So clash of gaming cultures plus the introduction of more user-friendly elements combined to create the idea of the PC Elitist.
But, frankly, seeing the way the wind is blowing. Console fans might be facing their own "Console Gaming Is Dead" attitude in the not too distant future. It's pretty much accepted that the next console generation might be the last, casual gaming is booming, and the cost of AAA games is so high that fewer and fewer studios can afford the expense. Might have Zynga fans bitching about Console Elitists in the not too distant future.
