I would disagree. Like, really,
really disagree. D&D isn't hackable. Well, it isn't any more hackable than any other tabletop game by the virtue of humans resolving all the rules and being able to agree to resolve them differently.
To be brutally honest, I can't help than to scratch my head in confusion every time someone says that D&D is hackable/flexible/just a toolbox. No, it isn't! Look at the rules! If a game "designed to be flexible" can't handle the most basic stuff, like "nobody really cares about this trivial fight, can we just condense it into a single roll?" or "we really care about this non-combat scene, can we add more mechanical gravitas to it?", then it failed miserably!
As an example of a "toolbox" game, let's take a look at Fate. The Golden Rule of Fate is that there are many rules that can be used to resolve any particular situation, and you must choose the most appropriate one.
Talking to someone can be (when I say "you", I mean "your character"):
- Nothing, if there's nothing substantial to be accomplished. You just say what you want to say and the other character responds: saying "Hi" to a friend; contemplating about the nature of free will while gazing upon the false sun; etc
- A single roll, if there's something to be accomplished, but it's not interestingenough to drag out:
- Overcome roll, if it's an obstacle to, well, overcome: persuading the bouncer to let you into the bar; getting your ma to let you sleep over at friend's house; etc
- Create Advantage roll, if the goal is to sow seeds to be used later: convincing someone that you are actually bitcoin millionare, so you can scam them; cheering up your friend with a "friendship is magic!" speech, so they can act at 101%; etc
- Attack roll, if your goal is to hurt them with words: making fun of an NPC; etc
- Defence roll, if they are attacking you, and you are choosing words to defend yourself: "please don't hit me!"
- A Challenge, if you want to focus on the process more: convincing Legate Lanius that Hoover Dam ain't worth it
- A Contest, if you and some other characters have mutually exclusive goals, but can't harm each other: making a case that it's your department that needs to receive a budget increase, not Janice's
- A Conflict, if you and another character can and want to hurt each other: an explosive falling out between lovers, "I'm the one carrying this family! Do you think we could live off your indie RPGs?! You will starve in a ditch!", "Oh, yeah, do you know why you still have that job? Because I'm banging your boss!"; etc
....and then there's Bronze Rule that allows to enable all the rules that apply to characters to apply to anything, but that's a bit too Fate-y to explain here.
And the same applies to any situation: swordfight, picking a lock, whatever. Fate doesn't say "any swordfight is always a conflict" the way D&D does. You consider the situation and what do you want to get out of it, and pick the most appropriate tool.
D&D doesn't work that way. It gives you tools of very limited applicability, doesn't explain how to use them, and then you are expected to hack something on the fly when the situation arises.
And even if it's not hacking per se, Fate allows you to adjust the level of detail whenever you create
any content. Let's say you need a monster. You write "Mind Goblin: 2" on a piece of paper, boom, done! You have a perfectly usable monster that has a single aspect (Mind Goblin) and a single skill (Mind Goblin) that it can roll if needed. Need more detail? Sure, you can add more aspects, create dedicated skills, add stunts, hell, create a separate statblock for each of Hydra's heads. If you need to.
D&D has two modes: you either just wing it, or you have a full-blown statblock. No in-betweens.