This analogy would be more meaningful if it weren't supremely possible to, as you say, "scribble" in the kinds of things described. And if people didn't keep having really negative responses to the abstract descriptions of what the tool does, only to follow that up with "...isn't that exactly the same as D&D...?" when you give them anything concrete.
My aim was to engage with the poster's analogy. What I think other posters are saying is that D&D is not a tool that can be operationalized in only one way like say a grout rake (I haven't yet thought of any uses for a grout rake other than raking grout... but who knows really.) The game text by design can be operationalized in many ways.
That means that if I say "Isn't that exactly the same as D&D" it might not be. Because the operationalization of the D&D tool or game-as-artifact that I'm picturing and that will be productive of my D&D play or game-as-played might be different from that which they are picturing. Just as one cannot predict that a given use of Photoshop will produce a fauvist artwork. (And equally, just as failure to produce a fauvist artwork on this occasion doesn't make Photoshop a bad tool.)
It just comes across as extremely tempest-in-a-teapot stuff. Freaking out over being told you have to play by the rules, and then finding out that rejecting these rules is actually a really, really bad idea 99.99...% of the time.
I might have missed that part, but I suspect the whole thing is deeply confounded. Play by
which way of grasping and upholding the rules. Reject which rules
taking into account how one expects to grasp and uphold those?
One way I think about it is this. Suppose I have an
ur-rule that says follow or don't follow other rules according to my principles. And suppose further that I haven't written down my principles
and yet I feel like I know what they are. Feeling like one knows what ones principles are is to my observation pretty common, and yet if one asks questions it's quickly obvious that there are a lot of differing principles in play and folk don't
clearly know what they are. They're fuzzy, flexible, complexly conditional. And suppose further that my ur-rule (the one bolded) says that what I should understand those other rules to entail also depends on my principles. Thus, overall I should grasp and uphold the rules according to my principles.
Most folk follow an ur-rule like that in their approach to TTRPG. Some game designers write out a list of principles they want to put folk in mind of. D&D doesn't. That directly and unavoidably implies that D&D resists common definition.