Why do you continue to post when you're so obviously and blatantly against 5e.
I think [MENTION=83293]nnms[/MENTION] poses a very interesting question - How well does the 'rulings not rules' approach sit within a set of robust rules? - and I'm definitely not anti-5e.
What Mike describes is actually the way I ran 4e. I didn't use the detailed skill rules, just DCs for Easy, Medium and Difficult checks, writing the values for these on my session overview sheet. I was quite unfamiliar with the 4e rules, I like a very fast-paced game, and I'm pretty comfortable making on-the-spot rulings. I wasn't using formal skill challenges, as I feel they don't add anything.
I can see how, if play is heavily gamist, which 4e often is, the players may not like this approach, at least if the quick DC is higher than the DC in the rules. But, imo, 4e restricts its gamism to combat, leaving other aspects of the game fairly freeform, much like B/X, or OD&D, so I think it would work for most people.
Rulings not rules would not, imo sit easily with 3e as the rules set tries to be very thorough. It's totally the wrong set of rules, imho, for a freewheeling GM. That said, such a GM could get away with it, if the players are easy going and prepared to cede authority. It could end up working a lot like 4e - krunchy kombat, open non-combat. Or it could go further, with the system being 3e in name only, and in actuality being free kriegspiel - no rules at all.
Old schoolers would say that the rules of OD&D and 1e are robust, because they are easy to houserule without breaking. Some might say that's because those rules were a mess to begin with, and can't be made any more disordered than they already are. You can't knock down a castle that's already in ruins type of thing. But that would be a separate argument, I think.