@Laralex "The rate limiter idea is also not good enough because users can change their IP address and post again." - yes, but some might not be as sophisticated, maybe that'll save 10% spam but that's still something.
I think what we need to realise, that unless you ID each user with the gov ID, you won't be able to stop it, I don't think there's an inpenetrabel system like he wishes there was, there will be fake reviews just deal with it, meanwhile he should focus on all of the advice given here.
Again, unless there's one global system where you need ID for everything, then there will be scam. What would stop the person from buying the products and living the reviews, its not like he will ship the product to himself, and he might get all of the money back anyway, unless that person doesn't manage to deduct it from tax or find a loophole or legal reason that it was himself that bough it from himself lol which would be also a good idea to make sure to have this in the website legal policy that prohibits this just to be covered in case that does happen. And I hope we don't end up where we need gov ID to log into interenat and use ID instead of email address... because the data will be abused by the gov since they have the interest of big companies and not the people and then welcome to dystopia and dictatorship, where if you don't smile and obey you end up life for prison or... But that's off-topic xd
Edit: Even recaptch and all that stuff, there are people in 3rd world countries that do this when they act like a robot. So again, unless you GOV ID people on websites, you won't be able to do this.
Just not possible. YT, LinkedIn etc... can't stop fake comments let alone him. And they are getting sophisticated recently. If you noticed the bots are having a discussion, literally have like 20 users(bots) write with each other with the crypto scam and all that not sure you've noticed, worse than wat it was a year ago.