From what I've been seeing, there are multiple books on this site with manipulated reviews. Bad reviews have been deleted and thus the books themselves appear better. Although I can understand that a review made based on ~10 chapters of a book with over 1,000 chapters may not be accurate, it is still an opinion.
People keep on saying that authors are deleting reviews, but as far as I can tell, I do not have that ability (it might also just be because I'm not partnered). Maybe those reviews are being reported as inaccurate by fans (yeah probably not).
The only thing that deleting reviews does is angering the reviewers. On a site like Webnovel, where everyone can review a book an almost infinite number of times, it's just a matter of time before such a book is flooded with bad reviews.
Advice for Webnovel, don't reward reviews with xp and limit the amount of reviews per book. A review is something that should be taken seriously and I find it highly unlikely that anyone would be willing to read a new book every single day (at least for an extended period of time).