Every business has good and bad interactions with customers. For most businesses the bad ones are unfortunate but isolated cases. For those where it's a pattern, they'll eventually lose enough business that they'll change or die.

What yelp has done is to artificially magnify the effect of an individual complaint. Most people don't bother to write publicly one way or the other, and (I think) people with a negative experience are more likely to complain publicly.

The effect of yelp is "world changing" in some sense; they make it easier for perfectly good businesses to go out of business. Not really what I'd want my life's work to be, but to each his own, I guess.