TwoSix
Everyone's literal second-favorite poster
This is half-baked early morning thoughts, so I apologize for riffing here a bit.These claims aren't true. I know, because I GM RPGs which are not Calvinball at the table and don't approach magic in particular, nor worldbuilding in general, in the way you describe here. (I'm thinking of Prince Valiant, Agon, Cortex+ Heroic, 4e D&D and Torchbearer 2e in particular.)
It's not mysterious, either, why this is so: none of the RPGs I'm thinking of elevate Unmediated GM adjudication of the fiction as a principle of action resolution.
This whole discussion is a little odd, in that some of the participants who argue for more DM empowerment and loose/FKR-style resolution are suddenly arguing for more codification, which is a classic player-empowering tactic. Likewise, loose magic adjudication is almost certainly a grant of authority to the DM, which isn't the way these discussions normally go.
So is there another aesthetic consideration here that's mixing up the normal lines of discussion?
Right now, I feel like the desire for strong magical definition is about handing off authority to the setting, away from both the players and the DM, and improving that sense of being lost in the setting, trying to get closer to fully immersed like a holodeck. What that other thread about play motivations would call Submission or Abnegation, the idea of getting lost in the play experience.