For the last eight years users over at Worldbuilding, we have been debating about whether or not it's acceptable to ask questions that result in list answers. To be clear, these are questions that, no matter how well focused, are fishing for ideas or brainstorming. On most, if not all other Stack Exchange sites, such questions would be acceptably off-topic.
The problem is that creating worldbuilding rules for imaginary worlds (e.g., my habitable world is the same size and density of Earth — but its gravity is only 75% of Earth's), and it often leads to dependencies that are unanticipated or misunderstood by the worldbuilder. This leads to questions that can have multiple possible answers depending on the nature of the worldbuilder's world (my Earth size/density planet only has 75% of Earth's gravity. How would that affect its moon?). In short, asking questions like this is very common during the worldbuilding process.
Unfortunately, common and useful as they may be, the one-specific-question/one-best-answer model used network-wide by Stack Exchange is too restrictive to allow those kinds of questions. But they keep popping up, both on Main and philosophically on Meta.
I recently asked a question about solving an ambiguity concerning brainstorming questions by promoting two possibilities: (a) We flatly prohibit brainstorming questions or (b) we permit them with conditions. Proposed modifications to the On Topic Help Center page were provided. Either choice would lead to less dissatisfaction and more consistent assistance to new users and moderation of experienced users.
And then one of our moderators asked a perfectly reasonable question.
Can we set a policy in the Help Center that permits a question type that's prohibited by one or more rules set by SE elsewhere in the Help Center?
Does Stack Exchange allow local Stack Stack Exchange sites to override (generally or specifically) any of the immutable rules identified in the Tour or any of the Help Center pages?
Example: Brainstorming questions are permitted even though they violate the prohibition against all answers having equal value.
If so, is it permissible to state that exception on the On Topic Help Center page?
Note: If SE staff state that individual Stack Exchange sites are not allowed to do this, then my question over at Worldbuilding is automatically answered.