I don't think that line in the help center applies to reference-request questions.
In most cases, if you really had to, it is trivial to connect those questions to an actual problem.
For example, the most recent reference-request is How random is the graduate admission process in the United States?. This question corresponds to the actual, real problem (for example):
"I am interested in reducing the randomness of the graduate admissions process in computer science PhD programs, but in order to convince anyone to act, I need some reliable, verifiable data to show how bad the problem really is."
In other cases, such as my reference-request question What is the origin of the “underwater basket weaving” meme in Academia?, where it is very difficult to connect the question to an actual problem, the community didn't seem to mind. (That question currently has 79 upvotes and 0 downvotes.)
So, it seems that a question does not necessarily need to be explicitly attached to a problem. I think reference-request questions that are clear, specific, and relevant to the topics in the help center are on topic here. (As evidenced, perhaps, by my being a top answerer and one of the top askers in that tag.)
You should only ask practical, answerable questions based on actual problems that you face.
mainly to exclude hypotheticals that lack context, where the answer depends very much on the specific circumstance.
To take your question Can I teach in the nude? as an example (I hope you don't mind), I commented there
Also, per the help center: "You should only ask practical, answerable questions based on actual problems that you face." This does not seem to qualify. – ff524♦ Jul 14 '15 at 16:54
and further clarified that I find the question problematic because it is a hypothetical given without context:
I don't think it would be a bad question if it was given in the context of a specific scenario, like this one. As a general question, I still think it's terrible. – ff524♦ Jul 14 '15 at 17:06
That's the kind of question I think is excluded by "practical, answerable questions based on actual problems that you face."