What bugs me is the assumption that "just about *every* campaign every DM ran assumed that Corellon Larethian put out Gruumsh's eye, that the drow fought the other elves and were driven underground, that Acererak the lich created a Tomb of Horrors somewhere on the planet, or that the Rod of Seven Parts was lying around someplace waiting to be found."
Now, when I played 1E, back in the day, it wasn't regularly, so I didn't have any set campaign world... but when I hooked up with my current DM a few years later and got into 2E, he used a homebrew world that he and his friends had been playing in since '77 or so. No Corellon; we had Gruumsh, but he had both eyes; no Tomb of Horrors (that I know of), and definitely no Rod of Seven Parts. Or any of the other artifacts from the book, for that matter - they made their own. We do have drow, and they did have a war with the elves and were driven underground, but they're albino, not black (yeah, I know, big whoop).
What I find amusing is that the designers assume that we'd crammed Faerunian gods (Corellon, Gruumsh) and lore (drow) in with Greyhawk locations (the Tomb) in this big mish-mash of a setting. And I'm sure some people did... but not "just about *every*" DM, I can guarantee. Lots of people played straight-up Greyhawk, or FR, or something completely different.
My point is that
...we've created a new skeleton of linked assumptions (proper names, artifacts, stories) to anchor the fluff of the "implied" setting.
might not always fit with people's homebrew settings. It obviously doesn't fit with FR - they have to shoehorn the ideas in. This has been brought up before: that not everyone will have an "infernal empire", that their settings already have a set history, and that they'd have to seriously retcon them to shoehorn in said empire, the war with the dragonborn, etc.
We're not actually building a world out of the "core" setting.
Now, for my own part, I favor the idea of sketching a simple map of that setting and thinking up a name for it.
So which is it, Rich? It seems to me that there IS a metasetting there - the history, the racial backgrounds (and most likely feats and skill bonuses tied to them), even the classes all point to it. Let's call a duck a duck and be done with it, hmm?