I posted a question on a fairly specific Java use case, and received a one-sentence answer basically of the form "what you have here is a special case of X." There wasn't any explanation of X, of why the case under discussion was a form of X, or how to apply X in the case; furthermore, while it might be true that X could be applied, it's far from straightforwardly obvious that X is the best approach or how to apply it in detail.
I downvoted the answer. The user who posted the answer asked why. I explained, perhaps not politely as I could have, but exhaustively. The user (who has 24K rep at the time of this writing) asserts that his answer is neither misleading nor unhelpful and that my downvote is "abuse".
Well, I didn't find it helpful. And while I didn't find it misleading, I didn't find it led me to an answer either.
I've been on SO for more than three years, and I thought the purpose of upvoting/downvoting was to highlight quality answers. Is there a norm that's arisen that I don't know about, that says downvoting is only for answers that are factually wrong, and low-quality answers that are not factually wrong should never be downvoted?
(The specific case is here.)