Campbell
Relaxed Intensity
It is when players can introduce new information into the game world. Narrativists would say they adhere to the agreed upon fiction boundaries but otherwise it's wide open. So a player could say, "I go into town and find my sister at the tavern where she works" and that would suddenly be a true fact in the world so long as no one had established anything to the contrary prior to that time. Obviously there are degrees in this as well but that is the simple one sentence idea.
This is just fundamentally untrue of games like Apocalypse World. The GM has framing authority. They just have restrictions on that framing authority and a differing agenda than simulating a world. 95% of the differences lay in how the GM role functions. My interface as a player in Apocalypse World is almost entirely the same as it would be in a more traditional game.
The GM/MC will sometimes ask questions to establish things, but that too relies on the GM actively asking in accordance with their framing authority.
We have been having these discussions for years and you have been an active participant. Where are you getting this from? Do you have posts or game texts to point to?