I am really new to the Stack Exchange community and after reading several answers, I seem to come to the same conclusion; that some fail to realize the scope of the question.
Now I'm unsure as to whether I misunderstand - like, whether or not there is another way of approaching this situation - but it seems as though the only real way to let an answer-writer know that they didn't read the question correctly is to comment on it. However, a flag would allow (maybe?) the answer to be filtered to the bottom of the question and allow new users to see how not to answer questions (this of course being more relevant for larger question threads, but I'm sure there could be other uses for this).
Encouragement for Better Answers
For an example of an answer, let's take a look at this question: Which house is the best investment to build up money?
Now it's clear to see that the accepted answer is beautifully written and quite a rigorous answer to a simple question. We can also see that the second answer is nowhere near this quality level, which is most likely a result of not realizing the scope of the question.
I'm not suggesting this as a way of punishing users for not understanding a question, I'm merely suggesting a way for users to understand why their answer wasn't voted for. In the given example this is obvious, but it might not always be so obvious.
I suggest that this be a passive flag (meaning it doesn't necessarily mean the user needs to be punished, merely monitored) that will, in a way, allow users to not only vote it down for it's irrelevance or whether the answer is incorrect, but also allow the user to flag the post for moderators to see that maybe this user needs help. This will then allow the user to learn from their mistakes and perhaps encourage them to rethink their answer and edit it to realize the scope of the question better.
Reduction of Unnecessary Comments
I go through a lot of questions just to read and see how other people answer questions, and I see a lot of people who tell people that they didn't read the question properly. I feel as though this takes up too much time and is really negative because the user would feel they are being 'hated on' in a sense. This flag would be a way of quickly doing this and also would be good for the user because instead of getting direct hate, they could instead see a 'tally' of how many people think they didn't read the question properly.
I understand that a lot of users just want to help and they don't mean to read questions incorrectly, so this would be a simple and (hopefully) effective way of reducing hate and misappropriated discussion in the comments and instead allow for community discussion to help the user understand the questions they attempt to answer better.
I don't necessarily expect this to be added, however I would like to hear some discussion as to why or why not this might be a good feature idea. Please share any and all feedback for this idea.