I personally don't value the opinions of people who just leave reviews out of a desire to see their words appear on a website somewhere (and the irony of writing this doesn't escape me).

I do agree with your view (directly below at the time of writing) that the root problem may be Amazon's refund mechanism which requires you to provide a reason. "Not as described" covers everything from "you said it was a book, I received a bag of carrots" to "I didn't understand it" or "I didn't agree with it".