I would hope that Yelp doesn't actually operate in the manner in which its detractors accuse it of (as it would seem to be pretty cut-and-dry extortion).

I assume Yelp operates in the way they say they do, but I still find it functionally useless as a review site.

Every once in a while I'll look up the reviews for a place that I frequent and like, and read the reviews. They inevitably show me that people's reviews might as well be random. If the reviews for places that I already like are this different from my own experiences, how useful can they be for places I'm thinking about going to?

It would be like if I read movie reviews from a reviewer who hates all the movies I like (or worse, is ambivalent). I wouldn't find reading their reviews useful.