Not my bag, but a lot of people here seem to want that for reasons I don't understand.
I doubt it is for lack of trying to explain it.
Do you understand the reasons folks want GMs to follow some rules, generally?
If you grasp that, broadly, then the rest is fiddly commentary about where to draw lines, and what helps the GM do their job.
Edit to add: a Douglas Adams reference about strictly defined areas of doubt and uncertainty would fit here nicely.






