There is no need to write credible reviews at the moment. When this need arises they will all be exactly the same as real reviews. Bots are already writing entire articles. Creating templates from "real" reviews is barely a challenge.
Was my review a real one?
You can argue it was real but can still be used to skew the results. People are more likely to give good reviews plus review sooner before it breaks or they discover something wrong with it.
I would argue that paying for reviews is inherently dishonest. So is giving away items for free for reviews.
(I didn’t bother reviewing the subsequent one I purchased)
Completely fake reviews have always been banned on Amazon and this is an article about how rampant they are.