There is a lot more "implied" setting in almost any edition of D&D than most people think.
The most setting neutral version of D&D produced was 2nd edition.
See, I respectfully disagree (for reasons I outlined in my original post).
OD&D? No setting in the book AT ALL! no map, nothing apart from a few random mage names, if that.
1e PHB/DMG/MM? pretty much nothing. It had a great wheel appendix in the back, but it was hardly central to the system, and was in no way prescriptive - it hardly had any relevance. Everyone 'knows' that Greyhawk was the implied setting, but only in retrospect - there was nothing that even hits at it in the original.
One of the things that made competitor RPGs interesting in the late 70's and early 80's at that time was that there were appearing with even sketchy campaign settings (one page map, one page potted history). Runequest benefited from being tightly coupled to its rather rich campaign setting, albeit only a fragment of Dragon Pass.
(4e, FWIWIMO overstepped the mark in their astral sea, ancient war between gods and titans, devils are this, demons are that, etc. etc. That isn't implied setting, that is nailing down a setting! 'Points of Light' was an implied setting. Fallen tiefling and dragonman empires is actual setting

)
Cheers