I don't think that's even Yelps primary value proposition. They're much more of a social network than anything else. Their proposition seems to be more around providing a place for people to gain recognition for their taste. This is why they have the elite yelper program and what-not.<p>The result of that play is a huge site with a TON of reviews that create a lot of organic SEO traffic. The credibility of those reviews, while important, isn't really their upmost concern.<p>That's why withholding positive reviews (under the guise of spam control) is effective. They're effectively extorting you to create more content for them.<p>Is it intentionally designed that way? I have no idea, but I bet it's extremely effective.