The review swaps are the reason why anything below 4.5 stars is unreadable garbage (usually). Review swappers rate a story highly so that their story doesn't get a bad review (no matter how honest they claim they have rated, it's in human nature. Sure maybe a couple of ppl are honest, but i doubt more than 10% are actually completely honest). The rating system needs to be fixed or changed (no idea how tbh), but many stories are utterly TERRIBLE while being rated 4.7 stars that just make my mind explode at how they could be rated so highly, so I'm particularly harsh on them, as clearly others aren't or are bot reviewed. Ugh i think i went a bit off topic. Anyway, while review swapping is good for new novels to get attention and reviews, they are not helpfully to a reader, as they are usually fakeish (yes I made a new word, deal with it).
edit: oh and ofcourse authors being able to delete negative reviews... Authors should only be able to report a negative review to mods if the negative review is pure bullshit and have it removed by mods, not having the power to remove whichever negative review they don't like.