I have seen a handful of questions get closed on ELL, and the close reasons usually start something like this:
I'm voting to close this question because it's about a rare or non-standard form of English that learners don't need to worry about.
(italics often in original)
This comment is often followed up with a link to an Ngram or a Google search designed to prove that the wording being asked about is rare, along with more close votes from native speakers.
Frankly, this rubs me the wrong way, and strikes me as condescending. I think it should be our learners who get to decide what interests them.
Our learners are trying to learn English from a wide variety of sources – classic books, new books, English language textbooks, children's books, news articles, internet discussion boards, television, and movies, and so on. As such, they are bound to run into odd phrases, strange words, and non-standard forms. This will often pique their curiosity – and they should feel free to ask about such expressions here. Moreover, we natives are here to help, and should make an earnest effort to NOT be so dismissive of such questions.
I have a theory about what's going on, and I'd like our learners to tell me if I'm right or wrong. I'm not fazed by questions that ask about a non-standard usage or word – because I'd surmise that such passages are more likely to prompt a learner to ask a question. After all, a sentence with no unusual words or constructs is unremarkable, understandable, and not puzzling at all. But passages or quotes containing something out of the ordinary are the ones that make a leaner think, "Wait a minute – now I'm confused."
These are exactly the kinds of question I believe ELL was designed to field, if we can just remember that:
(a) learners often have trouble detecting when a usage is an error, or something they simply haven't learned about yet;
(b) sometimes finding an answer on the web isn't as trivial as we think it might be – particularly when someone doesn't understand the original text or have a firm grasp on the language;
(c) learners are not solely interested in proper, formal, standard, textbook English;
(d) it's good to know that a mysterious construct is seldom used, but that won't make a learner's curiosity vanish.
It's one thing to put a question on hold because it doesn't have enough context, and needs to be fleshed out more. (Learners, please tell us more about why you're asking the question! The more you tell us about where you heard or read something, the more likely we are to understand your confusion.) But I don't think it's right to put a question on hold because it has a limited scope, or because it's asking about something we rarely run across.