It's well understood in the social gaming industry that if you want a hit game, you have to do one of two things: get an underground viral hit (very hard and impossible to predict) or you buy users through ads. According to a recent story, Zynga may be spending as much as $300 per user to be on top [1]. The actual number is irrelevent. The important part is they're paying more in marketing and ads than their competitors and see better conversion rates because of it.

Operations does play a huge part in keeping the customers playing (user retention), it's true. The game has to look slick and not crash. Their ops teams must be wizards. Their design teams, not so much.

[1] http://news.ycombinator.com/item?id=3494617