We used to have the close reason "too localised", whose text was:
This question is unlikely to ever help any future visitors; it is only relevant to a small geographic area, a specific moment in time, or an extraordinarily narrow situation that is not generally applicable to the worldwide audience of the internet.
It was considered to be prone to misuse, or at the very best its text did not match the message that the closing intended to convey (which basically boils down to the part before the semicolon). It was removed as a part of the closing system overhaul in June (reference).
With the overhaul, Maths.SE gained the ability to have custom close reasons. Currently, we have only one: "This question is missing context and/or other details" (reference).
TL;DR? Start here
My proposal is to introduce another custom close reason, similar in intent to the old "too localised" reason.
I imagine this close reason to apply to cases such as:
- Multiple questions in one post (relevant meta-thread);
- Low-level "specific instance" questions, of the type "What is $1+5-20$?" (relevant thread, particularly Pete L. Clark's answer);
- Questions obsoleted by time (admittedly rare on MSE);
and I'm sure there are more (although, as detailed below, I consider particularly the second bullet point to apply to a lot of questions already).
A bit more on the "specific instance" questions. There are quite some questions asking about problems that are (or at least, seem to be) designed exclusively for familiarising students/readers with definitions, theorems, and the material in general.
If such questions are not answered with something similar to the "exhaustively detailed general solution" type of answer, they are not likely to help future readers. In fact, if they are searching for answers to this type of question, we actually want to get the message across that they need to get their hands dirty.
Part of this is currently being dealt with by the "missing context" reason. If OP adds context, it's likely that some custom-tailored replies are posted to help them take any remaining hurdles.
On the other hand, many of these questions will -- once OP has been guided to the solution -- be of negligible value to future users. I contend that it is a good thing to weed out this type of question by closures. Don't get me wrong, I'm favouring the "helping OP" part of what MSE is, but I do think that for the "repository of mathematical knowledge" part of MSE it is beneficial to have a mechanism to weed out those questions whose merit is confined to the former aspect of MSE.
The new close reason would be a welcome aid to this end. (But even when this application is disregarded/disapproved of, I still contend that the close reason is useful enough.)
I would like to discuss the wording of such a reason in a different post, and confine the present thread to the discussion of the desirability of such a close reason.