Often times, I come across "answers" that are related to the question but don't answer the question that has actually been asked in the OP. Often times this occurs when the OP asks for an explanation of a proof, or how to finish a proof, and the answer gives an entirely unrelated proof. [The example has been deleted because it's not an actual example, see comments for discussion]
I usually downvote such answers and leave a comment explaining why, but it occurred to me that such an answer might be flaggable as "not an answer." Is that an appropriate action? Is that a better way to disincentive users who have a high frequency of answers like this than just downvoting them?