What is MO's exact policy on answering or not answering off-topic questions? Assuming there is some well-defined policy. My guess is: you are allowed to answer off-topic questions and if somebody provides a precise, detailed answer to an off-topic question, you should not downvote them. Downvote this post if you disagree.
EDIT: I should have clarified what I mean by off-topic. I mean the following situation: a person gives an answer, after they did this, the question is put on hold as off-topic (e.g. see here). Does their answer also become off-topic, or what?
EDIT: on the main site, YCor says that on this occasion the question was off-topic but the answer was not (since some theorem is not common knowledge). I think this is a non-trivial fact about MO. So answers to questions not of research-level can be research-level?
EDIT: at the the time of the edit, there are 7 downvotes for this question and the score of the linked answer is also 7. I invite the downvoters to downvote the answer so that their actions reflect their views.