I am replying this far back, as your back and forth with
@Maxperson is a dead end. You are right about that the roll determines the presence of the monster. However the difference is as we have sorted out hundreds of posts ago about the entanglement with player actions. A roll
purely to determine the presence of a monster is generally regarded as fine for everyone seemingly (even if not all are using it). A roll entangling the presence of a creature to a player chosen skill roll is not for someone that want a feeling of a genuinely independent world.
The key difference is the feel of independence of the world is tightly related to the independence of statistics. If a seperate roll is made for the presence of the cook, that roll is statistically independent of any characteristics of the character. If the presence of the cook is determined by the skill roll, then the probability of there being a cook
depends on the character skill. It is this
dependence that breaks the illusion of
independence
See the difference now?
EDIT: Sorry! I see now that it was
@hawkeyefan that kept this reply chain going.