The system and mechanics in an RPG exist to model the "world" in the game is set, and the desired feel and tone.
The setting, the characters, the tone, the feel, the genre, etc, those are all the actual TERRITORY -- the mechanics and system are the MAP.
I like this metaphor!
Always hated those "Crunch haters" and "We are pure role, do not need bloody mechanics" people.
We need both: crunch & fluff.
Unfortunately the authors of many recent L5R books forget the first word....