In a wider more pedestrian sense, there is a some kettle-pot-black involved here, at least in my opinion.
Yelp's a little monopolistic middle man. Everyone reads and writes reviews on Yelp because everyone reads and writes reviews on Yelp. Market dominance today is the main ingredient for dominance tomorrow. Everyone uses Google search, maps, phones etc. Google gets all the data & ad revenue. They use this to maintain their dominance.
Pick your euphemism for this position: momentum, network effects, buffet's moat, thiel's-monopoly, dominance, viral feedback loops.... Whatever you call it, a restaurant can't opt out of yelp, just like a website can't opt out of google. Their rules are the rules. There is no option B.
A downstream company can be harmed when Google competes direct (AKA the terror of 2006), when they redirect traffic to alternative web pages or disrupts market dominance downstream, intentionally or otherwise.
This is like Yelp's relationship with restaurants. Yelp can stop sending a restaurant customers. Google can stop sending Yelp users. There are no "market dynamics," no "invisible hands," price signals or whatnot. There is no "market" to impose discipline in the way the laissez-faire idealization does on paper.
So... I'm kind of torn. I want to see far more complaints, cases & legislation targeting market dominance, size and monopoly. On the other hand, the hypocrisy...