Imo it's useless. I do not like it. Ratings are there to let a person know what you think. Not to say cookie and walk away. That's just me, at least.
It's possibly a troll. Hopefully it'll be removed come next year :p I agree with @salamander9o , It's quite pointless
Well, what he did kina made the rating abusive... Check recent activity and you'll see how abusive the rating has become.
But its neutral, it doesnt really affect anything. There's no farming for likes so i don't see what maybe wrong.