Again, it depends upon what we mean by "D&D". Are we talking about the experiential/personal aspect that Mearls and I were referring to or are we talking about a literal/technical definition of the game? If the latter, I agree with you, if the former, I don't.
So you don't believe that rules changes can affect the way one personally interacts with the game? If so, I have news to you. I can say without fear of contradiction that rules changes can and do, since they are the basis for a lot of people's dissatisfaction with 4Ed because I have seen it in others AND personally experienced it. There is a reason I don't feel a connection to a "universal experience" that you and Mearls are touting: "specific rules" and "change(s) to the game’s mechanics"
have made 4Ed feel like a generic, non-D&D, FRPG to me.
So have other, non-mechanical alterations.
I enjoy playing 4Ed, I really do. I've been going stir-crazy about not being able to play my Dwarven Starlock so far this year due to travel and other RW issues. But behind that yearning to play Magnus Skyhammer is an urge to do likewise in some of our other campaigns in previous editions that I have a stronger "D&D-ish" feel from. Those games feel like "home" or "Rome"- the 4Ed game simply doesn't.
You just did it again, Danny - you seem unable or unwilling to discuss the first approach I mentioned, which is the experience/essence aspect of D&D which Mearls and I were talking about. What you do, and did again, is reduce that to a discussion of technicality and definition. These are two different things, different conversations really.
In some sense I am reminded of a neuroscientist who refutes the notion of "love" as anything but chemical interactions in the brain. That's their right to do so but it stalls conversation when someone is talking about love as something more or other or non-reducible.
I'm talking about something within the D&D experience (Mearls' "core essence") which is non-reducible to any formulation of rules, opinions, ideas, or concepts, and has nothing to do with my "Threefold Model" of primary, secondary, and tertiary. That is why I used the term "archetype" in the other thread. I am not saying that D&D is only an archetype, or that this is the only way that we can talk about it, but if we do talk about it as an archetype it takes on a different quality than if we're talking in technical, defining terms, and it also serves to be much more unifying because it protects the personal nature of the experience, yet with an underlying universality.
You just said that you don't buy this notion of a "core essence" so I would suggest that we let the conversation go, because in essence it seems that our disagreement is philosophical, even ontological. I do think we largely agree when we stick to the realm of technical definitions (the 2nd point I mentioned), which boils down to the Threefold Model I posited. But if you say that the first point is meaningless, let's just leave it at that and agree to disagree.
"Wikipedia
An archetype (pronounced /ˈɑrkɪtaɪp/) is an original model of a person, ideal example, or a prototype upon which others are copied, patterned, or emulated; a symbol universally recognized by all. In psychology, an archetype is a model of a person, personality, or behavior."
"Merriam-Webster
Definition of ARCHETYPE
1
: the original pattern or model of which all things of the same type are representations or copies : prototype; also : a perfect example
2
: idea 1a
3
: an inherited idea or mode of thought in the psychology of C. G. Jung that is derived from the experience of the race and is present in the unconscious of the individual"
If all that you & Mearls are discussing is that, there is still a problem because, as I've said before, 4Ed doesn't meet that definition.
To me and others, 4Ed does not connect to that universal feel of D&D in any way, and without universality, it does not match the archetype of D&D. At best, it fits into an archetype of
FRPGs in general. The universality you so want to claim is there simply isn't.
If we look to M-W's definition, 4Ed again fails to be archetypically D&D because it is a fairly big variance from its origins.