I was going to be an ass and link this to show that it's not the case for current gamers..
but I WAS WROOONG.
http://store.steampowered.com/hwsurvey
Second one on the left, shows that out of steam users (and let's face it, the vast majority of PC gamers have steam) just under 47% use dual cores, just under 45% use quad cores, and just over 5% use single cores, putting single cores in the minority.
What were we talking about, again?
If you saw what was written here before I edited, ignore it.
I haven't slept in.. too long, and am going to go do that right now.
... maybe after refreshing the GW2 subforum a few times.
(Guys, I have a problem.)