The open review system (anyone can review any item) maybe made some sense when it was just book reviews, but makes much less sense for all items. A good start would be to only allow reviews on verified purchases. At least then it would be much harder for bad actors to up stakes on a listing and clone to a new one once the authentic negative reviews piled up.
Verified reviews can be faked and gamed as well, but it is harder, more costly and time consuming.
Yes. I'm trying to remember back to early amazon, circa the bubble burst... my vague recollection is that reviews were more in the vein of a platform for book reviews, not review of books as products... a fine difference, maybe one wothout distinction when it comes to books, but an either way an open platform for book reviews has very different trust and reliabilty requirements than reviews attached to products being sold.
Verified reviews can be faked and gamed as well, but it is harder, more costly and time consuming.