You Ravenloft example is a good one using a familiar D&D setting rather than the literary examples like Middle Earth, REH's Hyborian Age, or even DL.
Different fictional settings bring different degrees of theme/tone with them. Eg GH has less than REH, but still - would a notionally GH game that didn't involve any of the S&S tropes (ancient wizards, Bright Deserts, oracular priests, etc) be a genuine GH game? This is partly why From the Ashes was contentious - it was seen as contradicting the tone.
And to echo something I mentioned upthread, I think that - of the established D&D settings - FR might have the least degree of theme/tone, and so the one for which "canon" correlates most strongly to an atlas and a chronicle. Which, I think, is one reason why it's never grabbed me.