I think you're intentionally missing the point, here.
No, you're missing the point.
The point is, that missions, exploration sites and other things of that nature, that provide bits of PF from time to time, means that every player's experience of the background is slightly different, and this creates a greater variety of RP stances.
You said you prefer everything laid out in books or a wiki. Which means every player and thus character, experiences the same background, there's nothing that they might encounter ingame to change their opinions on stuff. Nothing to explore in the universe. No sense of discovery. Nothing that might challenge your interpretation of the background.
which sounds a lot more dull and static and boring.