Exactly. It's dumb, but very real. The problem isn't whether it's warranted or not, it's about who's got deeper pockets. Most of the time, someone running a car forum doesn't actually have liability over what others post about a product review, etc., but when the dumbazz vendor sues the site owner, it's now a bunch of legal fees piling up to defend oneself from the company bringing the unfounded charges. Depends on your risk aversion, sometimes it's best to avoid all that.
Nobody is going to mute your freedom of speech. If you have a bad review, post it on one of those review sites or wherever. Go outside and complain to the neighbors. Or anyone who will listen. But it's also a two-way deal. I've seen people give bad reviews to a company or a product because they didn't go way outside the lines to give them comps or some other freebie or whatever other unreasonable demand wasn't met and then told the world how bad they sucked.
Example: You order 2 exhaust pipes from Company A. They send the exhaust pipes. When they arrive, one exhaust pipe is crunched and unusable. Probably UPS crunched it, but what do you do? You contact the company, and if they're worth their salt, they should know YOU didn't mess it up like that because why would you? You follow the company's policy for return/refund/replacement, and if they make good on it, you get a new pipe, everything is good. Some people out there would give them a bad review for sending a bent pipe in the first place. Which they very likely didn't. But they're too stupid to understand that's not how life works. Personally, I'd give them kudos for making things right even when it was UPS who screwed up. Believe me, UPS is a nightmare dealing with smashed boxes that they did.
But say this time you get a different pipe. WTF? Then you can start getting a bit miffed at their lack of service after the sale. If they continue to screw things up, and then if they're like some vendors who actually BLAME THE CUSTOMER for the problem, then that's where they get a bad review. Good or bad, reviews should be 100% truthful and factual. Opinions are fine, but the facts need to be there. Most of the time, your temperament can make a difference when dealing with the company screwups. They're human too. Ever make a mistake? Sure you have. It's how you handle things AFTER they go wrong that makes the difference.