Negative reviews in Yelp can be removed. That is what the flag is for. So the review removal infrastructure is in place.
I had a favorite sushi restaurant who would get the shakedown calls from Yelp sales. I was a regular and I remember the Mom+Pop owners complaining about the shakedowns.
Yeah I've reported reviews before because they were clearly purchased by the business (which was nose-diving and the real reviews showed it).
Yelp didn't pull the reviews because they couldn't prove that they were by people who are related to the business owners. They were all fresh accounts with no other activity, and all used the same style. Silly that yelp tags real reviews as fake but doesn't yank the truly bogus reviews.
I had a favorite sushi restaurant who would get the shakedown calls from Yelp sales. I was a regular and I remember the Mom+Pop owners complaining about the shakedowns.
But what Yelp does is apparently legal.