You're right that it's not unique to FR, but almost no matter where it's done, it's annoying. It's like the cliche of having George Takei answer angry continuity questions at a Trek convention. You've taken all the fun out of make-believe storytelling.
Now, that's the view from the outside. I'm well aware that some people have a lot of fun plumbing the lore depths of their favorite X. That's fine and good and neat and shouldn't be invalidated haphazardly in the official documents.
But you should be able to take off the truefan hat and enjoy the game regardless. If you can't, that kind of is a problem because it functionally means that no one else can make that setting their own. It's yours, not theirs. In D&D, that's part and parcel of the fun of running a game: adapting it for your own group.
As a less-dorky example, I have a roommate who is crazy into the Beatles. She gets really angry whenever someone claims to be really into the Beatles, and she kind of enters this one-upmanship of "who loves them more" with the person, an impromptu trivia quiz and rattling off of facts and things. This can be an issue, because she doesn't let people appreciate the Beatles on their own level: it has to be on HER terms, they can't have their OWN experiences with the band. I have to beat her about the neck and face on a regular basis for it, too.He's allowed to have his own Beatles experience. Your DM is allowed to run his own FR experience.
(Just a quick reply until I get home...)
Certainly, but don't you think the group should discuss these matters beforehand? If my group had diehard Eberron fans, I'd likely discuss any major changes (such as, say, replacing Mournlands with Ravenloft or the ruler of Karrnath with a paladin king) with them beforehand. Of course, you *can* just say "By the way, guys, the Warforged are evil in my campaign and you can't play them... either suck it up or walk out the door!", but there's a middle road to this. I'm firmly of the mind that every DM decides what happens at his table, but you should also consider the wishes and opinion of your players, too. For example, if my players hate WFRP, I wouldn't try forcing it down their throats; likewise, if they prefer dungeoncrawling and slaying monsters, I wouldn't run intrigue-laden adventures with multi-layered plots and dozens of NPCs. That doesn't mean you always need to say "Yes", either; the wisest thing is to discuss this in your group and find out what everyone wants out of the game. Is everyone okay if your next Dark Sun campaign features some major changes? Does anyone have a problem if you only allow stuff from PHB 1? And so on.
Sometimes you read the book and you choose to go a different route for your own purposes. For instance, perhaps the DM wants to put their own leader in charge so that said leader can be evil.
Sometimes you read it and you don't care for it. "Oh. It's boring to have the only public churches being non-Evil ones. Let's add some evil ones."
Sometimes you read it but don't remember it "What was the name of this king?"
Sometimes you don't read it because another part interests you more. "Nobody cares what the ruler's name is, because that's not what the game is about this time!"
The idea is, of course, that as a DM, you get to choose what exists and what doesn't.
The written material never trumps the DM's say-so, be it in a rule or in the fluff.
And here I see it coming down to gaming style preferences; if everyone is on the same page in your group and having fun, it's all fine and well. We do it all the time with minor stuff in my group -- as a player, I might occasionally recognise a local shopkeeper or high priest as being half the world away from his canon location, but I don't mind if it fits. However, having played in FR campaigns (in other groups) in which the DM not only changed the ruler of Cormyr without any other explanations than "I didn't want to read the book", he also managed to continually misspell the name of the kingdom (as Cormyrea, I think). As a DM, I always try to make the setting feel "alive" and internally consistent, and as a player I expect the DM to put at least *some* effort into his campaigns. Just as I expect adventures to have at least some sort of coherent plots and NPCs to behave according to logical motivations (beyond the 'I-am-Evil-therefore-I-kidnap-children'-type of senseless justification for a hackfest).