In fairness to your point, I also find that Amazon reviews can no longer be trusted, and I really try to buy as little as possible from Amazon. Due to this, and other reasons, I find it quite difficult to have a good sense for whether I've bought something high quality, or if it'll be a piece of trash.
Drifting off topic now, but Amazon could easily implement a few measures to really lock down reviews, but they purposely leave it gameable because it drives sales.