Because we just don't have the population to support it, not to mention most of us here in PC are not THAT dedicated enough to use 300 dollars on a picture of a gangsta-wannabe dragon on a piece of cardboard for a children's trading card. Most of us are either casual players IRL, or only play on DS (I'm with Alter Ego on that, DS only.)
If we do duel, then usually it's either on DS, or on MSN using infinite card pool. As for honesty with infinite card pool, you just have to trust the person to be really using random number generator properly for that. I play using the MSN infinite card pool thing, and I trust my fellow friends in this super small YGO community in PC to be not cheating and pull off a Jaden Yuki every moment.