Why there isn't a way to vote for a Bad Answer (thumb-down) ?

Yes, I know like in Facebook there is only a “Like” option, but what if you want to mark “this is a bad answer, ignore it” ?

If lots of people think “this is bad” the questioner can use that info and ignore that answer, or at least know it isn’t the best one he can get.

I understand no one likes to receive “Dislike” or a bad mark on his answer, but it may be helpful if you think about it. Isn’t it?

I see lots of web site don’t use the thumb-down option anymore, I think it is because they think about the “Like” in Facebook, but in Q&A it does has a value for the users. It is not personal, our privacy is kept here.