...and no one knows what to do to fix it.
In 2010 the new Web was all about "user generated content". Today, the modern mantra is: "Don't read the comments"
Reviews and review sites have almost exactly the same problems as comment sections: there is no way to filter the ignorant and/or malicious from the informed and sincere. Case in point: there are currently exactly two reviews of my book on Amazon. One from a reasonably thoughtful reader (3 stars) and one from a troll who apparently has given Charles Dickens the same rating as me (2 stars).
There was a five-star review which was from someone who had read the book and genuinely liked it, but Amazon determined it was from someone I knew (likely because I bought her a book on the site a few years ago) and removed the review. This is a ridiculous practice--it would invalidate a huge number of reviews in traditional publications--but is made necessary by authors who try to game the review system in the stupidest possible way.
If there is a solution to these problems it's likely some kind of reputation system, but as near as I can tell no one--not Amazon, not GoodReads, not TripAdvisor, not Yelp, not anyone--is even thinking along those lines, which suggests there is no money in building a site that provides honest peer-to-peer feedback. This is a shame, because the Web should be enabling us to help each other, not increasing our distrust of each other (we're plenty good enough at that already).