In reality, Yelp doesn't play games with reviews. I became the top-rated business in my city for my niche while turning down their sales people over and over. I successfully got one review removed in that time because it was clearly a spam account based on their review history. I have several legitimate 5-star reviews from actual happy customers on my business profile that "are not currently recommended" due to Yelp's aggressive anti-cheat software. There are plenty of unhappy business owners who would have people believe their poor Yelp ratings are because the game is rigged, and I'm sure Yelp makes plenty of mistakes, but it is not pay-to-win.
That’s not a counter argument. I was once the top rated player on a pay to win game server without having paid anything. The issue with pay to win in games and online reviews is the distortion not the impossibility of success.
Yelp etc needs the average review to be somewhat useful so people actually trusts the Star ratings. However, they can still accomplish that while distorting a significant number of reviews.
This thread is full of people with no first-hand experience repeating rumors and suspicions. No, I cannot prove a negative, but I don't think speculation is compelling evidence either.
Yelp has successfully defended it’s self from several such lawsuits, on the other hand it’s also been sued several times over this. So, it’s a little past just internet rumors.
The simple fact Yelp lets companies pay to highlight a favorable review is IMO enough to destroy their credibility. Worse they directed customers through GrubHub for an unearned commission which is as far as I can tell simple fraud. But, that’s not what people are alleging here.