These are not universal truths. They fit great in how many play a game like D&D. In a PbtA game, where everyone (including the GM) "plays to find out", defining that much ahead of time is counter to some of the concepts of the game.
Looking at the Gamemastering Principles of DW, the very first one is: "Draw Maps, Leave Blanks". Here's what the SRD says:
In that type of game, what you are describing is against how it is supposed to be run. The Principles are much stronger than DMing advice from the DMG, they are basically rules for GMs where breaking them is akin to cheating just as much as a player fudging their dice in D&D is.
None of this a critique of D&D. Just exposure to the fact that other styles of games explicitly do not follow some of the assumptions D&D does.