Addendum
Some Puzzling stalwarts have mentioned in chats that they both:
Is this a pattern? If so, it seems both:
Puzzling. Why would someone who enjoys mathematics, as do I,
not enjoy its presentation, by someone else who enjoys mathematics,
for enjoyment by others?
Echoes: Mathematical problems are inherently puzzles;
very rarely does someone try to cheat a homework assignment here,
isn’t that what Mathematics SE is for?
Unfair. It only takes a handful of unimpressed experts
to deny an enjoyable taste of structured mathematics for many others.
Echoes: Downvoting and commenting are much more appropriate measures
for expressing boredom;
restricting mathematical puzzles does not improve the site
for many visitors, mainly just for those who vote to close.
Original post
Yes, mathematical 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 mathematics problem.
As in incomplete.
The linked Meta post offers no suggestions on how to
improve the presentation of a mathematics-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 drill an 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.
Mathematical puzzles can become focal points for displaced frustration caused by
other unappreciated puzzles that don't have specific close buttons.
Some newcomers have been chased here from Mathematics SE
for presenting what have been perceived as puzzles.
Need we add insult to injury?