Is someone claiming that water is oil?
The point is that, for all the variations Mercurius delineates for water in her analogy, none of the definitions or tropes includes oil. All are clearly water in some way.
She has not been so successful in excluding non-D&D games from her "experiential" definitions of D&D.
Good question. What are your thoughts on the matter? After all, these non-D&D games could certainly be converted to pre-4E rules D&D. So what makes D&D "D&D" in your opinion?
Like I've said a few times, I haven't seen something that can be described as uniquely D&D on the purely "emotional"/"experiential" level that Mercurius has been asserting exists. I can define it mechanically, yes. Legally, yes. But Mearls'/Mercurius' "D&D Experience" is, so far, so nebulous as to be ungraspable.
I can and have run D&D sims in HERO that emulated vorpal weapons, Vancian casting, D&D races, etc., that delivered the same "feel" as I got playing 1Ed-3Ed D&D. I've also played many FRPGs that don't, 4Ed included.
So, despite Mearls'/Mercurius' assertions to the contrary, I can only say that "feel" derives from the aggregation of tropes, the rules, the fluff of the game, how the PCs use their resources- all achievable in a variety of systems, some of which are not legally or mechanically D&D. And because that feel is not unique to legal/mechanical D&D systems, there doesn't seem to be a truly unique "D&D Experience." At best,
at best, you can say there is an "Experience" that is predominantly found in D&D, but is not unique to it.
Unless, of course, Mercurius can provide some form to the "D&D Experience" that convincingly excludes experiences found playing non-mechanical/non-legal D&D sims.