This question already has an answer here:
What does the
not an answer flag mean?
My interpretation is that this flag is intended for things which clearly are not answers. In other words, "this shouldn't exist, because it does not intend to answer the question".
It's the difference between a value judgement ("how good is this answer?"), handled with voting, and a clear "this shouldn't exist (as an answer)". The latter is junk that either should have been something else (e.g. a comment, edit etc.) or is clearly worthless (e.g. spam).
I think that downvoting is the mechanism for dealing with wrong answers, answers that answer the wrong question, or irrelevant answers. This is important because a moderator may not always have the context to know whether an answer is helpful or not, or may just be wrong. In my opinion, a mod should not be authorised to make such a unilateral value judgement.
Is this correct? Are there circumstances where making a value judgement for this flag is acceptable? I'd like a canonical ruling or community consensus to point to for reference for such flag declines.
(Context: I am a moderator on Board and Card Games. I have a repeated mod flag where the OP believes I should delete the answer because it doesn't answer his question. However, I believe it is a good faith answer, and I'm happy to watch it stand or fall on its merit. It requires me to understand the question to know whether the answer is or isn't sufficient. I think it is outside of my jurisdiction as a moderator/human exception handler to act.)