The whole point, as I see it, of ruling vs rules, is that you rely on the GM to tell you how the interaction with his world works, and the rules are a support for the GM to do this... as opposed to the rules defining how you interact with the world. To me that is a welcome change of pace, and a nice return to the "old days".
How would you characterise the following rule:
When you consult your accumulated knowledge about something, roll 2d6+Int bonus:
✴On a 10+, the GM will tell you something interesting and useful about the subject relevant to your situation;
✴On a 7–9, the GM will only tell you something interesting—it’s on you to make it useful;
The GM might ask you "How do you know this?" Tell them the truth, now.
I don't see how it fits into a dichotomy between "the rules supporting the GM telling you how your interaction with his/her world works" and "the rules defining how your interact with the world".
My reason for asking is that because I don't think your suggested dichotomy covers the field, I don't know what you're trying to tell me about adjudication in 5e.
DnD isn’t a narrow game. It isn’t quite generic in the sense that GURPS is, but it is generic in the sense that it deals in goals on a campaign basis, rather than on a total system basis.
DnD is meant to be played by groups that was dungeon crawling and groups that want courtly intrigue, and groups that want both, in one game, from session to session. This is part of why DnD is so popular. It is very well constructed to be a game that can have multiple goals, and let the group simply choose the win conditions.
I think a courtly intrigue game of D&D is almost certain to involve issues around Charm Person and Suggestion spells - particulary if it's a game using the AD&D versions which (by contemporary standards) are super-high powered. At mid-level there will be ESP and other divination-related issues too (which 2nd ed-era stuff solved (for some value of "solved") by giving all diplomats a Ring of Mind Shielding or similar).
(The above is not theorycraft. It's extrapolation from experience.)
Character builds that support dungeon crawling (high capacity to absorb ablative damage; magic oriented towards fighting and exploration challenges; etc) tend to leave other aspects of character underdeveloped. The contrast even between D&D and Classic Traveller (1977) in this respect is fairly striking.
Another difference between D&D and other games that I personally would see as more versatile within their genres is that
so much real estate in D&D is taken up with spells and, in later versions, similar discrete list-selected class features (feats, powers, the range of class abilities in 5e). The difference between a paladin and a ranger
could be the difference between
gain advantage when your honour would help and
gain advantage when your knowledge of the wilds would help, but it's not.
(Also, and despite the name, GURPS is not especiallly generic. I think it offers a pretty consistent and fairly tightly focused gaming experience, of slightly low-powered Hero.)
