Thought — when the GM is expected to do the vast bulk of the story generation, even based on flags the players give them, system-driven premises can get in the way, and players mostly need to know what carrots and sticks look like.

When multiple people are expected to be driving the story, knowing the premise and having it supported by the system is an important tool for getting everyone on the same page. See Fate or Spark’s campaign creation rules.

So — when one person, or maybe two people are doing the tale crafting, individual skill matters most — and that’s highly idiosyncratic.

It’s only when you need to herd a bunch of cats that making this stuff explicit to the whole group helps.