(After a fruitful conversation with Deusovi but before taking the time to waylay this with endless edits.)
Yes, math problem closure should be discontinued in its current form,
and no, its intent should not be abandoned.
1. At the very least, the hold/close message should be revised from its, well, crude, present form:
This question is off-topic as it appears to be a mathematics problem, as opposed to a mathematical puzzle. For more info, see "Are math-textbook-style problems on topic?" on meta.
Crude?
As in rude. “This question is off-topic” can be an unwelcoming slap in the face to a novice puzzle pos(t)er. We do not need to haze newcomers.
As in unrefined. The word problem is unnecessarily ambiguous. And the claim that a question is off topic is inconsistent with the explanation that the question appears to be a math problem.
As in incomplete. The linked Meta post offers no suggestions on how to improve the presentation of a math-oriented puzzle. That was never its purpose. At best, it provides some examples that could serve as morals, none of rehabilitation, a handful of barely-acknowledged abstractions, some comments that might or might not help, and a link or two that lead to more of the same.
Here is a first pass at a better rejection message, also crude at the moment but less rude. It could, for one thing, benefit from an even more encouraging tone. Please help by editing or adding alternatives.
This post appears to be more of
a drillan exercise [problem didn't seem specific enough] than a puzzle. For ideas on how to present it as a puzzle, please see [same link as now until we devise a question specifically for this?].
**2.** The criteria could be broadened to include *all* drill-like puzzles, regardless of relative frequencies. The example above allows for this. To single out “mathematics” provokes human fallibility:
Objectivity is limited as we don't consider how the same criteria apply to other puzzle subjects that we might happen to enjoy more or, even, care about less.
Math puzzles can become focal points for displaced frustration caused by other unappreciated puzzles that don't have a specific close button.
Some newcomers have been chased here from Mathematics SE for presenting what have been perceived as puzzles. Need we add insult to injury?