They described asking the player what their character does, so I don't think that's quite true. But even if we ignore that, I don't think the rules actually do contradict the spirit of what they propose.
Asking the players to decide some bits of what happens in the world isn't outside the RAW, as far as I can tell. It seems to all into the very broad category of things that are up to the DM.
However, even if it is outside the RAW, it is good for the game when played in the way that the OP describes.