I am done with the "if you don't like it don't read it" reply to any negative review on a novel. Look here, If I am posting a review on a novel saying I don't like it, do you think I'm going to keep reading?
Let me give you an analogy of why I hate this in the first place: I find a guy posing an ad for free cookies in front of me (novel description), the reviews are pretty good and the cookies look good too, but when I bite into it and I find it is filled with chocolate and blueberries (spelling, grammar, or serious plot holes, poor story, you get the idea) I say i -not anybody else- don't like it. Then someone near me says then "then don't eat it"
Do you understand me now?
Rant end
"If you don't like it, don't read it"
I rarely give out reviews so don't snap at me for saying your "i don't like this book" probably offended someone who really loves the book. They strongly support it that they don't want to see 1star reviews for it because in their eyes, it's a perfect book. Just be the bigger person and don't mind them. Better yet, if you don't like a certain book just don't bother leaving any review so you won't get pissed by the fans who would then gallantly defend the book. 
Just write what you want since they're doing the same thing. I go on Yelp when my service is bad so if I waste my time on some crap novel, I should also inform people.
The only time i feel like such a reply is understandable, is when people give reviews that go along the lines of "yea the grammar is good, plot is interesting, and the characters arent 2d. Overall a really good novel. Too bad i prefer stories with more romance :(" then BAM! 2 stars.
When its those readers, they should really look at the tags and synopsis, and then decide not to read it. Other than that, the idea of "if you dont like it, dont say anything about it" is ridiculous.