Allow me to express a dissenting opinion (it may turn out not to be as dissenting as initially thought, but bear with me).
Comment First off, I think you were absolutely right to leave a comment suggesting the duplicate. Even if the OP had already tried that solution, at least others can benefit from finding it. This is especially useful since the original question mentioned other questions and answers without linking to them.
Early close votes I would refrain from voting to close (or flagging) as a duplicate so early, though, doubly so without input from the OP. Timing and "premature voting" have already been discussed extensively on meta. Definitely in the early stages when it is likely that the OP will respond, duplicate suggestions should not be used to suggest to moderators to evaluate the question, but should rather suggest possible solutions to the person asking the question. In this particular case it is doubtful that anyone besides the OP could evaluate the merits of a possible solution from the original version of the question. The idea here is that especially so shortly after a question has been asked the primary concern should be to help the user and solve her problem, while concerns about "keeping the site clean" should come second or third.
That is not to say that I never vote to close. I think it is perfectly reasonable to vote to close if the OP agrees that the question is a duplicate (assuming I agree with her) or if there has been no reaction for a while and the question is deserted.
MWEs I would like to take up the "insistence upon MWEs" from your title. "Insistence" has a slightly negative ring to my non-native ears, so please allow me to comment on that as well. It is true that many people on this site (including me) often ask for an MWE if a question lacks one. It is also true that not all questions require an MWE to be understood or answered (Are there questions where we can recognize that a MWE is not necessary?, automatic check for MWE). Even then an MWE can be helpful to get started and test possible answers, so while I am "guilty" of asking for an MWE even if it may not be "required", I at least try to make it clear in my comments that this is the case. On the other hand, there are many questions that I believe cannot be answered properly without seeing an MWE (Why does TeX require such elaborate MWE:s). While it may be possible to guess the right solution, there are just too many variables we don't know about. MWEs are particularly helpful if the OP confuses package names or other terms in the text of their question or in the tags (e.g. "I'm using
natbib" when only
natbib compatibility mode is used,
biblatex vs BibTeX, adding the LaTeX3 tag for no reason, ...).
In this case the OP mistakenly tagged their question with the
biblatex tag and mentioned that package explicitly in the title and body of the question, even though they actually used the BibTeX style
ACM-Reference-Format.bst. This only became clear after an
MWE excerpt of the preamble was posted.
I appreciate that the OP had time constraints and that they may not have been able to invest time into making a truly minimal MWE, but I believe that time is better spent creating an MWE than being sent on a wild goose chase of possible solutions.
Answering duplicate questions Like David I believe that there is absolutely no harm in answering a question even if it is indeed a duplicate. If writing an answer is quicker than finding and linking a good duplicate, then surely that can only benefit the OP. If the new answer puts a different spin on things, or shows how to implement a solution in the context of the new question then that is fine as well.
I don't really see the point in restating an answer if there is little additional value to be gained from doing so and the duplicate link is already at hand, as was the case here. If there would have been an MWE, additional value would have been gained from implementing the answer with the given MWE. I personally would only have added such an answer after the OP replied that they had problem getting the suggested answer to work, but if you think that the OP benefits from that right away, who am I to stop you?
What I do object to, however, is simply copying over an answer (I'm not suggesting you did that, this is purely to explain my views). That does not really add value to the site or the OP. The OP is only one click further from the solution if you simply link to it. Even if they are really pressed for time, I cannot imagine that being a huge disadvantage. At worst, copying an existing answer is harmful because it means that two answers spread outdated information after a while (one seemingly being more up-to-date than the other), and it means that two answers need to updated. In case the answer has flaws or bugs, there are now two places where they can be reported.
Copying over only bits of an answer might work, but if done badly can actually combine the two disadvantages of simply linking and copying the answer. Originally https://tex.stackexchange.com/revisions/422015/1 was not really helpful without the link to the existing answer, since there was no indication whatsoever as to where the code changes needed to be made. This is worse than a simple link because the answer gets the OP's hopes up and requires cognitive load to be processed, only to then find out that the answer lies elsewhere. In that case a simple link and a short note to look there would have been more efficient.
I appreciate that this particular case has not been very kind to your approach.
- It turned out that an MWE was actually useful, since it cleared up a confusion about
biblatex vs. BibTeX.
- The suggested duplicate was not actually the suitable answer here.
- The answer in the suggested duplicate was improved by updating.
If one or more of these had turned out otherwise, in hindsight your approach would have been more successful.
My strategy for cases like this is to ask for clarification/an MWE, so that possible answers can be found and evaluated.
If I know of a possible duplicate, normally I only leave a comment with a link and maybe a short explanation. I suggest you do not flag or vote to close at that point. Instead wait for a response. If the OP is happy with the duplicate, flag and vote away, if the OP agrees it might not even need to go through the normal review queue.
If the OP has trouble getting the suggested duplicate answer to work, I'll then proceed to post an answer.