In deciding whether a question should be closed, moderators and users of sufficient reputation refer to the official physics S.E. policy, and act accordingly. In law, if a particular decision is approved in a case, it may provide a precedent for future cases. Suppose a question on the physics S.E. is by the policy off-topic, but a previous question many years ago, which was upvoted, untouched by moderators, and answered is off-topic by the same argument applied to the present question. Does the fact that the question was allowed previously provide precedent? If not, should it?
Note: the question is purely a 'thought experiment,' or perhaps more appropriately hypothetical. I'm interested in hearing different perspectives on this topic.