TL;PR
The help center gives some positive guidance about on-topic matters, and some negative guidance about what not to do. There is a specific point about the "Not 'Please make me a tree'" rule which I raise in my answer, the gist of which being that I don't think it is clear enough what constitutes a what-not-to-do. It was suggested that I raise the broader question. I find the guidance a bit too minimal, especially in terms of giving functional explanations for the guidelines that would allow users to better filter and frame their questions. My underlying assumption is that people will better understand what to do if they know why that's what they should do.
One question is whether "do my homework for me" questions should be allowed. IMO, they should not be: and we should say so. However, there is nothing in the help center (about, on-topic, dont-ask) that suggests that this place isn't among other things a free answer-giving service. On-topic starts by saying who LSE is for, but not what purpose it serves. This was pointed out as the second point in this meta-discussion. The off-topic list stipulates that syntax trees, translation, and foreign-language learning help are out, but no reason is given (it also fails to include "language identification" questions). I would exclude such questions as having no general value -- knowing that Իմ անկյուն ցավում է is Armenian or that it means "My elbow hurts" is not a fact which can be applied to any other scientific linguistic inquiry. IMO, a question should be about something conceptual and general.
There is a discussion of homework questions here, and I don't see any support for answering people's homeworks for them. Some of the points raised in that discussion are that questions about homeworks should show signs of "making an effort", and that in principle, such questions might indirectly point to a question of general interest, so "How do you draw 'I want to go home'?" might lead to a question whether "go home" is a VP, but it also might lead to a question about S dominating "to go home". Might in principle, eventually, but doesn't, when framed as "How do you draw this tree" (there are analogous issues in phonology, morphology, historical etc.).
I believe that we should explicitly say "Do not ask us to do your homework for you", while admiting that homeworks can lead to appropriate questions. Then we should relate homeworks to what a good question is, specifically saying something to the effect that in answering a homework, you may discover that you don't know a specific think about the problem, like you don't know how to employ the concepts "phoneme" versus "contrast" in your answer, and this leads to a more general question -- the question that you should ask -- of what the difference is between these concepts. This would be a good (enough) question because the answer applies to any number of specific instances. We should relate homeworks to the desideratum of "showing some effort", saying something like "explain what part you do understand, and what alternatives you are considering", though I would frame this in terms of providing context, to which we should add "Make clear your framework assumptions", since analysis questions have many answers, depending on whether you're doing Categorial Grammar, Minimalism, Classical Aspects (anybody??), HPSG, LFG, or whatever.
So my suggestion is that we need some higher-level (help center) identification of the purpose of the site, and some elaboration of why asking for homework answers, translations and language identification is contrary to that purpose.
{ADDENDUM} Here is a recent example of someone asking for a solution to a phonology problem, and an exemplar of what should be off topic.
