Here's the question that prompted me to post this Meta question:
My question is how we should handle questions of the form:
How can I do A without using X or Y for some reason that I don't understand?
when nobody considering answering the question has a good answer for why you would ever not use X or Y to do A.
I expect that for the vast majority of these questions, the "some reason that I don't understand" is "because my teacher said so without explaining why", but I think it works to broaden the question just a bit. Maybe "my teacher" will sometimes be "my boss", "an article I read", or "the guy in the next cubicle".
There is a sister set of questions that differ from the set mentioned here in that there is an understood reason to not use X or Y, that reason being to explore or prove competence with the use of Z instead. I don't know if that set of questions should be addressed here at all. My main thought as to those is that it should be clearly identified in the question that the reason for the question, and potentially certain answers, is purely academic.
An alternative to answering the question right away would be to work with the OP to improve their question before attempting to answer it, hoping to move it out of the category being offered here before it is answered.
Is providing an alternative approach to a problem ever justified if the approach can't be technically justified under any foreseeable circumstances?