#17, who'd you check? People on the internet? That's like going to an amputee ward in a hospital and concluding that there's a high trend that humans have missing limbs. It's called a bad sample, in statstics.
Like it or not, single player is still the most popular gametype out there, because not everyone has broadband yet to enjoy multiplay, and not everyone has computers capable of running multiplay. Sure, if you look on the internet, it looks like everything is multiplay. That's because the internet is the damn medium multiplay works over.
That's as silly as saying that blue is the most common color because your homepage happens to be set to Blue's News. Or even better, that FPS games are the most popular (another huge misconception) because Blue's News happens to cover them more in-depth than other genres. "Bad sample".