Maxperson
Morkus from Orkus
First, I agree with Hussar. When I think of a setting, I don't think solely, or even primarily, of an imaginary geography and history. I think of tropes, themes, broad-brush backstory, etc.
This is why I've been able to play Oriental Adventures - the same setting - using two different sets of maps (home-drawn one, inspired by the description in the back of the original OA book; and the ones published by TSR).
This is why my Greyhawk games don't always involve the exact same backstory. Eg in my current GH game, Slerotin is the name of a Suel figure of some importance whose mummy was buried in a pyramid in the Bright Desert, and then at some time reinterred in the catacombs of Hardby. I can't remember if Slerotin eve figure in my other GH campaigns, but if so certainly not in this manner.
Okay, but this is not typical definition of setting. The typical definition of setting includes the geography and history. An OA setting without that geography and history is not the OA setting. It's a homebrew asian setting using the OA mechanics.
Second, the fact that a given setting, grounded in a given set of canonical texts, can nevertheless produce these quite different responses and interpretations is, in itself, evidence that @I'm A Banana's hope of ensuring conformity by reducing or elminating additions/changes to those texts, is unlikely to be realised.
Conformity is nearly impossible where you have a whole bunch of elements that have subjective aspects to them.
What I think RPG settings can usefully do is (i) handle some of the grunt work (of drawing maps, coming up with names, etc), and (ii) provide a ready supply of what I'll call "trope implementations". So if you want to play some sort of sand-and-sandals/sword-and-planet thing with evil overlords and mind powers, Dark Sun gives you stuff that implements those tropes. If you want to play spirit bureaucracies and kung fu, OA gives you stuff that implements those tropes. If you want to play something fairly Conan-esque, with wizards of ancient empires in a mash-up of pseudo-mediaeval European/Mediterranean/West-and-Central-Asian lands, GH is an alternative to the Hyborian Age itself. These tropes, in turn, tend to feed into the themes of the game.
This is what I mean when I talk about "using a setting".
You run your games differently than most, and I think that's skewing your perception of what a setting is. What you are describing is the creation of a homebrew setting that incorporates elements of other settings.
I think this is probably also why FR has never appealed to me - I've never seen what particular trope implementations it is providing me with.
The FR is a high adventure and high magic setting that uses real world cultures as models for the various nations. Cormyr is roughly England, and Mulhorrand is roughly Egypt for instance. Spain, France, Aztec and others are spread around as well.