Remember, everyone, if you aren't paying for it, you might be the product. In this case, a Yelp user is the product that Yelp sells to businesses by featuring 5-star reviews and burying the 1-star review.

Featuring the 1-stars and burying the 5-stars would also be quite the incentive for a business to pay Yelp, but it would be cynical to assume they are doing that, too.