Should questions about special cases of a more general problem be marked (closed) as duplicate?

Question

While browsing new questions asked on this website, it is common to find some of them as duplicates of older ones, and it is then generally productive to indicate it as such, and redirect the OP to the post where their problem was already discussed and solved.

However, I sometimes witnessed a tendancy to mark as duplicates questions about a special case/simpler case of a more general problem. For instance, recently someone asked about Gauss lemma in arithmetic in the context of integers, and a user here suggested that it is a duplicate of an older question discussing Gauss lemma in the context of polynomials.

When I first saw the above situation, I felt like it is not quite right, and I've started wondering whether questions about special/simple cases of a more general problem be marked (closed) as duplicate.

If the OP asks the question formulated in this very special case, it is most likely to me that they are not aware of the generalization. Now, there could be two specific reasons for this. Either the OP just didn't know about it, and it would be enriching for them that somebody points out their problem as a special of a broader statement ; either the OP does not have the mathematical level yet necessary to understand the more general statement. In the first case, such a question may indeed be marked (closed) as a duplicate, whereas in the second, I feel that it would be wrong.

Going back again to the example I gave above, because the OP explicitely asked about Gauss lemma using the formalism of integers, it seemed to me that they probably didn't know about abstract algebra neither about polynomials. Redirecting them to a more general version of Gauss lemma then seems conterproductive to me.

I would like to know what your thoughts are on this matter, and what would be the guideline when such cases occur.

Thank you for reading my post.

EDIT: Eventually, as I found back the question I am referring to, it seems that the user who suggested it was a duplicate deleted their comment. Even though my example may not be relevant anymore, I guess that my interrogation still is valid and maybe could refer to something you also already witnessed.

Answer 1

I think a rule of thumb is that if you can in the span of $1-3$ comments mention how the question is a special case of a more general question (without relying on too much jargon) then it is worth flagging as a duplicate, and if the user is feeling generous, maybe even leaving said comments.

Otherwise, even if SE is intended to be a repository of knowledge, if either hobbyists or undergraduates have no way to access that knowledge because everything is done in maximal generality, we are probably failing in that goal.

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I think usually for copy/paste questions that are overly specific, the rule of thumb can be applied to mantain quality of the site and also possibly direct OP to resources that cover some of the terminology for searching SE or google.