Well, I wrote three 5 star reviews during the last year, and I put a real effort into them, giving others tips how to avoid common mistakes when using the product, and correcting common misconceptions. I could do this, because I know this class of devices well.
The outcome was in every case, that I got a message back, that Amazon has to check and approve the reviews, which never happened. It's obvious, that they either don't want thorough reviews, even if they are 5 star, or are just not able to understand them.
After that, I understandably stopped to write reviews. In fact, I deleted my Amazon account, because I had some cases of defective products and dubious dealers, in which Amazon wasn't helpful at all, and that seems to become more and more common recently.