Why is it that only lists of works are off-topic? See for example this question, which has answers that are just as useless as those to a question asking for lists of works. Surely all questions asking for lists should be off-topic, regardless of what is being listed.
List questions are not necessarily off-topic just by nature of being a list question. They are off topic because, in most cases, list questions don't have a definitive answer. There's a lot of related questions on meta, including my own, as well as this earlier one.
List questions that have a short, finite, and objective set of answers that can be easily listed and explained are more likely to be on topic that lists that may change, that have lots of answers, or where membership in the list of answers is subjective or debatable.
The question you point to is actually not a very good example of an on-topic list question; I would call it "borderline acceptable", primarily because there's a chance that the answer may change, since the show is still airing new episodes. However, historically, the list in question changes very rarely, so it's not likely that the answer will change very much, just possible. It also meets the other criteria for a "good" list question -- the list is short, finite, and there is a simple and objective measure to determine what belongs on the list.
Lists of works, on the other hand, usually fail to meet at least one, if not several, of those criteria. Questions like "lists of movies with a strong female lead character" not only changes every time a new movie with a strong female lead character is released but can lead to arguments like "is the lead character in Nymphomaniac a strong female character or an exploited victim?". Those things make the question unanswerable, so it becomes off-topic by definition.
In the end, it's a very subjective decision by the community if a list question is "answerable enough" to be on topic or not, but it is a per-question decision. It's definitely not as easy as "lists of works as off topic, other lists are ok."
The off-topic close reasons contain an "other" category which "list" questions which are not for lists of works could go into, but my own feeling is that they - in cases where they are objectionable (which isn't always) - are more usefully closed as "too broad".
The example cited in this question seems valid to me because it's finite and because someone with a good familiarity with the work in question could produce an answer. Of course, that answer may be rendered invalid by future events in any ongoing series, but it's still an answer.
That to me establishes the key criterion:
- Is it actually possible to answer this question?
List-of-works questions can only be a "no" here because nobody has read every single work, and there may be one (or one million) obscure work(s) which fall through the cracks for whatever reason.
Other list questions aren't so cut-and-dried, but if of sufficiently narrow scope are answerable and may seem valid to remain open.