In every other web forum I have ever asked a question on, with every question I will enevitably get at least one truly unhelpful reply, telling me my whole approach is wrong, asking me why I am using my language, platform, operating system, etc. instead of their favorite, telling me I should go back to progammer's school, etc. Mind you it's not just me, everybody gets them. Anyway, I don't see those here. What happens to them and their authors? Does your cousin Guido pay them a visit :)
They're around. But you see them less, since the rest of us like to delete their answers: just about anyone can "flag" a comment or answer for removal, and down-voting also helps to discourage this sort of thing and can encourage users to delete their misguided responses.
That sort of behavior is usually inappropriate... If you do encounter it, flag and ignore.
When you talk about "unhelpful people" are you talking about truly unhelpful people, or people who only seem unhelpful because the real answer is the one you weren't looking for?
The former tend to get flagged, deleted, and/or down-voted to oblivion. The community tends to deal with these types fairly quickly.
The latter sometimes get down-voted to oblivion, sometimes they end up as high rep users.
Legitimate cases of where the asker is taking the wrong approach are pointed out. The
<center> cannot hold it is too late.