Edit: An incredibly valuable example of why we should add "This is a high concept question" to the VTC reasons is this question: What would happen if the salt in the oceans disappeared? The OP is even in the process of disputing the closure. In none of the currently visible comments is there a link to the "high concept question" Meta page, explaining why the question is off-topic.
A high concept question is a question where a vague premise leads to the question "what happens next?" (E.G., Let's say the Nazis invented the atom bomb before WWII ended, how would that have changed the outcome of the war?)
We get a lot of high concept questions. They're generally closed as "too broad" or "too opinion-based" or "too story-based" (or, in the current vernacular, not enough details or not enough focus). But this question type is so specific (somewhat like "too story based" questions) that I believe it deserves its own VTC reason, because I think most people who ask them don't realize what the problem is.
Question: Is it both possible and reasonable to add "This is a high concept question" to the list of community-specific reasons to close a question?
It should be noted that when a question is closed for lacking details, which (by definition) basically describes a high-concept question, the text in the closure-reason box is:
Closed. This question needs details or clarity. It is not currently accepting answers.
If you follow that link, you'll discover that it explains the old reasons (too broad, etc.) and none of the new reasons. So while I thought that an alternative to the problem might be to modify that help center page, the reality is that the page is already obsolete. What this means is that users (especially new users) don't have a way to understand the problem. From their perspective, they asked a perfectly sensible question. This is why I'm recommending adding a new VTC reason, which would include a link to the high concept question page.
Too Story Based means querents must provide a story (i.e., story-based conditions) for the question to meet Help Center rules.
High Concept means respondents must provide a story to answer the question.
Both of these reasons are specialized versions of "too opinion-based" but differ in that high concept questions are always too broad (violating the so-called book test, "Your questions should be reasonably scoped. If you can imagine an entire book that answers your question, you’re asking too much.") However, both of these sub-types are so commonly asked and have such clear explanations for why they are a problem that, IMO, they deserve their own entries.