Ok, maybe "crap" is a bit of exaggeration. The point was that you really wouldn't need to really struggle to make a great game, as people would download it just because they saw good (fake) reviews. As long as it doesn't really suck, there won't be negative reviews to counter this.
Anyway, I wonder how long will it take before this tactic becomes too widespread so that only huge players will have enough cash to game the system like this.
Fair enough, I think the amount of reviews (and buys) influences your position too so just the absence of negative reviews isn't enough.
I don't want to sound cynical, but why do you think it hasn't already spread so wide that only huge players can game the system enough to gain the top spots? There was an article on HN this month about how book publishers even game the NYT book rankings.
A crap game doesn't get good reviews, so boosting the app rating by buying fake reviews is just throwing good money after bad.