More to the point in litigation the online reviews would be not be admissible evidence since they are hearsay if used for the purpose of proving that what the review says happened is what actually happened. There might be some other use of them that would be admissible, in which case they'd not be completely worthless.
Of course if the writer was identified and located and could be brought into court to testify their statements on the witness stand could be useful. A statement on the Internet is not verifiable, by itself, that it even speaks to a true incident or the author is a living person. .
Okay....
37 or 38 years ago - something along those lines, I was a car wash manager. Some of my memory cells still work so I will share some. We probably had a claim every week for damages. The car wash then had big rotating nylon brushes - much tougher than the car washes today. 99.8% of the claims were due to faults on the vehicle. I remember one claim where the car wash punctured a tire due to a jagged piece of metal on a rail.
People would drive there cars around for a few days at shopping centers, work, school, etc - never inspecting, just hopping in and driving. Then they go to a car wash, run through it, and then inspect their cars for the first time in a week. Guess what? The see a scratch on the passenger side and believe it was the car wash. All the while cars are continuing to go through the tunnel without incident.
People would claim scratches with rust in them were caused by the car wash.
Had a claim for a flat tire with the steel belt showing and no tread - woman wanted a brand new tire.
Had man drive up, hop out, forget to put his car in park, car took off through the tunnel banging into everything, hit the blowers before they could pull up, windshield got smashed, car jumped the curb, went through four lanes of traffic, jumped another curb, into a Kmart parking lot, and stopped when it hit the wall of the store. Man claimed car wash threw his car those 1000 feet and wanted his windshield replaced.
Chrome pieces come loose, antennas break away due to age of vehicle...heck, go up north and look at the rust under those cars.
But probably the best was the car which threw a rod while in the car wash and guy blamed the car wash for causing his car's engine to go bad. Car had 180k+ miles on it. He didn't just want a new engine, he expected a new car. Yeah, we rejected his claim....