As DMs running a setting there is no one in a better position than us individually to control what gets put on our table. It could be a setting established by others, a homebrew the DM made up, the results of a game of Microscope by the players.
If a group decides that we all want to run a classic King Arthur flavored campaign and the DM starts bringing in warhammer goblins half way through because he like doing silly voices for them, the rest of the group dang well get to be arbiters of "Real True Thing" and ask to bring it back on course.
Certainly within your group you ought to come to agreements about the world you're playing in. But you only get to decide that for you and your table. You don't get to make sweeping pronouncements about what is and isn't "really" a given setting to the community-at-large, based on the criteria you've decided is essential to the world.
On the other hand, if we want to run an original setting then the lore is of that. But the lore that accumulates still is the lore for it and needs to be respected.
"Needs to be?" Dude, come on. Says who? The lore is a fiction; our actions don't offend it.
Adhering to what's been established has certain effects that may or may not be beneficial, or desirable, to a given table. That's up to the group to decide.
If you establish early in the game that there are only three dragons in the entire world, and then when they gain a bunch of levels you have them fight a party of foes all mounted on dragon-back, it's breaking it's own lore.
Or it could be that something interesting has happened that supersedes what was "known" before. If the thing is cool, and what it introduces is fun and there's a reasonable way to retcon it in, then I'll almost-quote the magnificent Peloquin and say "F--- the lore."
And last I checked we live in modern times, so it's okay to pay attention to something modern? Ask your player if you'd rather you were consistant or inconsistant with how you portrayed your setting and I think you'd find the former.
No one is stopping you from valuing what's important to you. The issue is that what you've been saying here suggests you think it ought to be just as important to everyone. You don't get to make that call.
(And my players and I are cool, thanks for asking. If something started to contradict their assumptions about what they thought they knew about the world, they'd trust me that it was intentional, that there was a story reason for it, and that it was in the service of Cool Stuff. We've earned that trust of each other in our time together - starting with when I first asked, "How much do you mind if I depart from canon?" and got the response, "This is
your world. Go for it.")
I *never* said those would be bad settings to run in. Putting words in my mouth and then arguing against them, in italics to make your point more forceful is a rather lame piece of rhetoric.
I said they weren't the Named settings. If a friend comes to me "hey, I was inspired by Eberron's magi-tech, but instead of dragonmarks I've got these cool ideas of ancient rune magic, plus I brought in this caste thing from this series of books and this map someone on EN World made for free use." I'd be there in an instant. But he's not running Eberron, nor is he running the setting from the books. He's running his own setting with it's own lore that he's (or we're) making up.
I'm afraid I wasn't clear the first time around, because it's the idea in the second paragraph there that I was addressing. What I'm saying is that I think it would be a fun experiment to say, "I think I want to run an alternate Eberron without the Houses and dragonmarks,"
and call it Eberron, and that it's ... unpleasant to respond to that idea with, "Well, but that's not
really Eberron so you shouldn't call it that."
Again, what you see as essential to the setting isn't universal. Just because it isn't the setting from the books doesn't make it not be a variation on that setting, obligating you to change all the names.
(Yes, if you change enough things, eventually it's no longer even vaguely recognizable as the original, and so you may run into communication problems if you discuss it outside your circle by calling it the original name. But so what? Sure, there's probably some ineffable moment when if you fiddle with enough parts of Eberron it eventually becomes not-Eberron; I'm unqualified to delve into the philosophy of that question, but confident in declaring that the moment almost certainly does not occur with the first alteration, and probably not the second, either.)
If I may: What does it hurt you that someone, somewhere might be running a game that you'll never see in a way that you wouldn't like? Because that seems to be the subtext of a great many discussions here, and I am at a loss to understand.
Really, what is a setting except the lore about it? If the lore egregiously doesn't match, you don't have the setting.
Again, this gestures at a false dichotomy. There's a lot of room on the slide between "everything is excruciatingly canonical in every detail and particular" and "really, you might as well just call it something else." And a lot of space to breathe before we get to "egregiously."
Almost any setting would still be itself without some specific detail about its lore. Probably several such details. The lore defines it, in part, but does not constrain it - not if it's a living milieu. And if it's in the service of a game, it better be living.
As an aside of my own: what I find amusing (well,
one of the things I find amusing) about the insistance on all-or-nothing adherence to setting lore is that the game setting most infamous for giving canon-detail headaches - the Forgotten Realms - was designed so that any particular detail of its lore could be discarded. That's what Elminster
was - the voice of a potentially unreliable narrator whose word on anything at all might be true, or partially true, or a misdirection, or an outright lie. And that's the default setting for D&D - one that was built with a device that assumed you were going to make it your own anyway, so you always had an excuse to contradict what was in the book. I love that, and I love that Greenwood was a clever enough architect of his subcreation to make that explicit. But it's also a device that works for just about anything.
Because that's the nature of stories - and that's all "lore" is, is stories. They change over time with their tellers. They start to contradict each other. They're slippery and capricious; they serve the ends of one master, then another. You need them, but you can't trust 'em. They change the world - and sometimes they change it so that it was always different than how you remember it. They
cannot be objective. And they're still all we've got.
And
that, best beloved, is why, in the end, there's no such thing as "canon."