To me this is my biggest disagreement. Not just for D&D and RPGs, but any game or sport anywhere. I don't have a problem with house rules or homebrewing. I think hombrewing in fact is a temperature gauging the health of the hobby. But Rule Zero is bad game design in every respect I can think of. But I have come to respect your opinion over the years and if Rule 0 is that vital to you I'd like to know why.
It's vital because when all the other rules break down (as they inevitably will, once subjected to what the players dream up) it's all you have left.
It's vital because D&D, unlike pretty much any other game I can think of, is (or should be) malleable and shape-able to the moment; both by coded houserules and by on-the-fly rulings. Many times you've said, as above, that "any game or sport" works in manner x and thus D&D should as well; I counter by saying the malleability of the rules is one thing that makes D&D specifically *not* like other games...which renders your comparison moot.
It's vital because most of the other broad scope "rules" are (or should be) no more than guidelines, and rule 0 is your tool to make the game function within those guidelines.
It's vital because the DM is not just a CPU taking in data and churning out results; she's a living breathing part of a living breathing game
For me this is simply not possible. Games are codes. The DM has a code, a hard solve, behind the screen. The players are gaming in to achieve self determined objectives within it. (The game itself like Chess is too hard to solve for it to be a puzzle) The DM could try and play it like a player does, but for me it always comes down to a referee running Mastermind trying to play both sides of the screen. Are they purposefully supposed to forget the code? Are they supposed to pretend they don't know what's going on behind the screen? They simply don't have the opportunity to be both IMO.
D&D is not Mastermind, nor is it Chess; nor Monopoly, nor a whole bunch of other things.
Again, you're trying to shoehorn D&D into a perception you have of how games (should) work, except D&D just don't work the same as all those other games. WoW is a code, written by a bunch of programmers; ditto for Baldur's Gate. But tabletop D&D is not a code, 3e's best attempts notwithstanding, if only because the whole thing is (and must always be) far too open-ended for the "code" to ever be complete.
Lan-"if anyone ever deciphers the code, please let me know"-efan