And that's what I'm talking about with "Say yes." and clipping out the borders. It allows them to run the game with very little mechanics comparatively but not a lot of GM-just-says because the default is for the players action to continue until it bumps up against a Move.
This is not what goes on in most more traditional rules light games, and while its not my cuppa for various reasons, it doesn't contain the same problems from my POV.
Well, again, I think
@pemerton said it a lot better than I did. The GM makes a move, and that move might imply that whatever the player did "drop a box on the rat" worked, or didn't work, but it is fundamentally 'about' executing the GM's part of the process of play of AW. So, expressed in GM moves, announce future badness, take something away, provide an opportunity with a cost, etc. Again going back to the rules quote of Pemerton, something which is the 'start of action', not the 'end of the action'.
The GM is primarily in a position of assisting in generating momentum, of moving the game along on its trajectory towards whatever is in store. It is this sense in which AW is a 'Story Game', NOT in the sense of the participants 'authoring a story' by their play. The story focus is in terms of momentum, of the flow of the process. Every time a player acts (which 100% of the time necessarily involves some action by their PC, remembering something, thinking something, etc.) the GM then bats the ball back into their court by responding with some kind of potent situation. Now, eventually things will reach a peak, a point where direct consequences accrue, a HARD MOVE. Sometimes the hard move is just 'making it real', other times it will produce some local finality in play. Maybe someone dies, some resource is irrevocably lost, some goal is attained, etc. At that point a GM move might be to spark a new cycle, here's where things like bringing in a 'doom' might be most likely to happen. "Yeah, you killed the marauders and secured your food supply, for now. However, strange noises are coming from the wellhead and the water is coming up murky with some reddish stuff..."