I have other reasons not to upvote that question, but I would not downvote or vote to close it either.
The official reason for closing many a question is "off-topic -> missing context". Some users mistakenly equate "missing context" with "missing work/effort shown".
The linked question gives context on the first line - it is from an Iranian math contest. I didn't read further, but if the contest question is worth its salt, it follows that 90%+ of our users will be clueless about how to solve it. Therefore it is pointless to demand that the asker would show their own work. This is in sharp contrast to questions about calculus/elementary number theory (or below), when 90%+ of our users can solve the question without breaking a sweat. In those cases the demand for other kind of context is essential for the purposes of gauging what kind of an answer would be helpful - and also to enforce the community norm against outsourced homework assignments.
[taking off the moderator hat]
- I am somewhat in favor of various subcommunities, say, those forming around selected tags, within Math.SE developing their own norms. Enforcing such norms will mostly be up to the subcommunities themselves. It is good to have some common standards (enforced for example via our common review queues), but IMO the keen followers of a tag are best placed to judge many cases. A good example of such a subcommunity is the one built around those tough definite integrals discussed recently.
- I am biased in the sense that IMO the higher level questions should be given some slack (in terms of how much effort needs to be shown). Partly because such askers may more often be in self study mode, and usually already know the basics anyway. Against that is (as pointed out to me by a fellow moderator, I think it was Arthur, but I'm not 100%) that such users really should know better than to copy/paste a homework problem - possible foreign language obstacles notwithstanding. So, let's be reasonable :-)
- It makes me angry, when a user who has earned their rep doing trigonometry and (pre)calculus suddenly feels qualified to judge that this question on, say, elliptic curves, "does not show any effort". IMO ideally anyone casting a "no effort" -close vote should be able to solve the problem themself. I am aware that the policy I suggested may place too high a burden to the first close-voter. That's where that ideally came from.
- This would lead to a certain kind of expertocracy. Call me an elitist pig, if you want to.
- I do practice this myself as much as I can. For example, I will skip all the questions in review queues when I don't feel qualified to judge the merits of a post for the above reasons. This applies to questions about for example stochastic processes, set theory, logic, functional analysis,..., you name it (after taking a peek at my profile). Of course, I could just copy, say, Did's close vote about a post in probability theory, but such a vote would not carry the weight of my INFORMED opinion, so it is surely best that I abstain from voting on such a question. Now that my votes are immediately binding this point has additional weight.