Why don't append a reason why the question is closed as a duplicate?

Question

Recently my question (link) got closed by someone who marked it as a duplicate of his own question asking a reference request. I supposed the answer of my question was on the article. So I looked inside it and I couldn't find the answer, and it was long paper. Maybe I lack the knowledge to understand it, so I asked why it was closed. I got no message. I asked on the duplicate about some things I didn't understand, and no answer.

I edited my question several times, but none were considered reasons to reopen the question.

I don't think this is how duplicate mechanisms should work. For me this is like someone answering an exercise of calculus by saying it is the book. So I propose that a reason why close a question as duplicate should be giving. At least some short one.

Answer 1

In the case of an exact duplicate the close as duplicate should be "self explanatory" as Nij remarked above. But there are a couple of wrinkles worth mentioning.

In many sister Communities the criterion for marking closed-as-duplicate is weakened to a proposed target Question (one of) whose Answers contains sufficient information to resolve this problem. At times a user with enough reputation will vote to close-as-duplicate here (Math.SE) using such weakened criteria.

But there may be some details to be supplied about how the proposed target can be used to solve the problem at hand. Writing such details in a Comment conflicts with the dictum that Comments are ephemeral content. If such details seemed at all non-obvious, my preference would be to post an Answer linking to the proposed duplicate and explaining how it solves the problem at hand.

On the other hand there are cases where it is obvious that the proposed duplicate has an Answer that solves the problem at hand, but that is not self-contained enough to satisfy new Readers. The situation described here seems to a version of that, where a specific problem posed gets redirected to an Answer responding to a reference request.

Citing a book or other lengthy resource can be a good reference request answer, but a specific problem often deserves a specific Answer. I'm in favor of keeping content of that kind open on Math.SE.