hawkeyefan
Legend
Exactly, as combat mode is one of the key situation the rules of D&D 5ed is not really delegating rule making power to the DM. Rule 0 is technically still in play, but the procedures at work in this mode is so tightly defined by the book that the DM cannot really say anything without coming in direct conflict with explicitely written word. This as opposed to the out of combat mode where the words mostly step out of the rules making, and rather uses suggestive language.
Right... if a GM usurped the combat rules, they better have a strong reason for doing so, or else be ready to face some dissatisfied or frustrated players.
Now, I'm not saying that the rest of the rules need to be as complex and varied as combat, but I don't think having clear procedures is a bad thing. I think it was @gorice who mentioned the NPC interaction rules that almost no one uses. They're clear in the DMG, but as was pointed out, almost no NPCs in the published adventures or monster books include Traits, Ideals, Bonds, and Flaws.
That's just really strange.
The other key situation i see where the written text actually is opiniated to a point where it is hard for a DM to come with rules assertions for similar reasons is character creation and advancement.
How so? I expect I agree, but I'm curious to hear your reasons.
I think the above serves as a rough answer to your question. If you allow players to create a character according to the character creation and advancement rules of a D&D edition, and accept to follow the rules it lay out for combat - I would say you are recognizably playing D&D. If you make any modifications to the procedures gouverning any of those two aspects of play, I would say we are looking at a somewhat different game.
I remember not too long back there was a discussion about B/X D&D and how much more focused it was than 5e, and why... and someone was arguing that wasn't really the case, and when asked why they explained it was becuase they've never used inventory/encumbrance rules.
And I was left thinking well of course they seem the same if you ignored the rules that may have made them seem different.