We had some discussion a long while back about the differences between questions about language (language learners stuff, word requests, the whole shebang - stuff that would be on topic on SE's language specific sites) and linguistics. It's a really interesting discussion, but didn't really go anywhere towards clarifying what the "main purpose" of this site is - are we a linguistics site first, general language site second, or the other way around? Those are the sorts of questions that will guide how we deal with separating questions, if at all.

It seems to me that even after nine more years we haven't grown (in the volume of traffic) to the point where it would be clear that any particular splitting or excluding would be likely to produce lively, compact, more focused communities.

There's no objective, easy to check boundary between "language" and "linguistics" either. For some people, their own language(s) are "language" and foreign languages are "linguistics". For some people, narrow questions are "language" and broad questions are "linguistics". For some people, single-language questions (no matter how advanced) are "language", and 3+ languages questions are "linguistics". And so on. Linguistics is simply the study of language.

It may happen that some subset of the traffic will grow to the point of becoming dominant and then it might be worth looking at what defines it and see whether it deserves a site of its own, with a narrower scope than what we are currently advertising.