Earlier quoted context omitted.
Review bombing isn’t just negative. People also review bomb their competitors with positive reviews in order to get their competitors’ listings taken down. How do we stop that? The harder we police against fake positive reviews, the more we incentivize this sort of anticompetitive sabotage.
I mean some straight-forward ones might be... Accounts need to verify themselves somehow. Accounts should be old enough before contributing reviews. Accounts should only be able to review X amount of titles an hour/day/etc. Moderators should have tools to identify influx of reviews and decide mitigation strategies. Moderators should be able to put up a banner on a title that may be review bombed so the community can…
Maybe you decide that sounds too difficult, so they should stop banning listings for that and focus on policing the reviews themselves. But that actually turns out to be a very difficult problem in itself! Sellers of crappy products will often include notes that induce/bribe the customers into leaving fake reviews. A seller of cheap products can rack up thousands of verified purchaser fake reviews this way.
They can also do things like hire a botnet to purchase the product in bulk using thousands of hacked PCs all over the world and get those PCs to review the product, generating more fake verified purchaser reviews.
In the end, if you don’t ban sellers for fake positive reviews then you run into these tactics and it’s very hard to police individual reviews. If you do decide to ban sellers then you have the opposite problem of dealing with sabotage.
As for detecting “influxes”, that problem is far from trivial. If a review bomber is using a botnet of thousands of PCs then it’s quite trivial to stagger the timing of the fake reviews over a period of weeks. It’s not like they’re forced to push a button and have them all hit the review page at the same time.