This makes no sense to me either. The BW mechanic and the Traveller mechanic are almost exactly the same:
In Classic Traveller: I'm looking for someone who will sell me illegal guns at a good price. Referee: OK, if you make a Streetwise check at <insert throw required> you find such a person.
In Burning Wheel: Is Evard's tower around here? GM: If you make a Great Masters-wise check at <insert number of successes required> then yes, it's around here.
Before the action declaration, the existence of
someone who will sell me illegal guns at a good price or of
Evard's tower is a mere genre-appropriate possibility (we know it's genre-appropriate in Traveller because the game includes worlds with specified law levels and includes characters with abilities like Admin and Bribery and Streetwise; we know it's genre-appropriate in Burning Wheel because the game includes characters who are sorcerers and summoners and witches and augurs and they have abilities like Great Masters-wise.)
And if the action is successful, in both cases it is established that there is, in a concrete sense known to the character,
a person here who will sell illegal guns at a good price or
Evard's tower in this general vicinity.