First and foremost:
A. It is not Yelp who votes on the business that has been reviewed
B. If there is a negative post then you as the business person of the reputable company must put forward your proofs to rebut the arguments made because if your business is reputable then you must do everything to see it maintain its reputation and refute all negative arguments made.
C. One cannot blame the site because then one must blame every single complaints site on the whole of the internet who are simply a forum (FORUM) for posting and they are NOT doing the posts themselves which is the whole point of the matter.
D. Yelp is still beneficial because once used for the right reason it can help warn and remove businesses who do not belong in operation at all-just like every other complaints site can. For e.g. alcohol has a good side and a bad side. Alcohol in some proportion is used in cough syrup medication to help with coughing-that's the good use, but people use alcohol to get hangovers with it and even obtain liver cancer with it-that's the bad use.
....So do we throw away alcohol from every cough syrup formulation or every cough syrup bottle that is in every pharmacy because people are getting drunk from it? Ridiculous!
As the saying goes "Don't throw away the baby with the bathwater..." truthfully here applies
Again... For Goodness Sake Make Sense!