Players often extrapolate connections between small details in the provided world. This creates content that they consider implicit to the canonical game. Other groups may possess a fundamentally different understanding of the setting that is equally consistent with the information the game provides.
For these reasons, the setting that one group plays in is not the setting that another group plays in. In effect, role-playing games in their static published form do not describe a specific fictional world or story. They describe a large multidimensional space of fictional worlds and stories organized by unifying data.
Rebecca Borgstrom, Structure and Meaning in Role-Playing Game Design
C’est l’évidence même, mais il n’est pas inutile de le rappeler.