Personally I dont buy products to "sort it out" myself. Sure I can steal ideas from even terribad products but that still is no excuse for just blowing stuff up at random.
An author writing something they think is better than what came before isn't "blowing stuff up at random". It's giving me their best work.
In one situation you chose to kill Nerof Gasgal. There was action involved. Unless your players are sociopaths, you put him in an adversarial role and a position where he could be killed. In the other instance, you had no choice. Someone else removed Gasgal.
And if you're running a game where Gasgal was a major NPC and player in your setting and you buy this supplement - which seems perfect for your game - and the Mayor is different, it throws you off.
Like Shasarak's "blowing things up", there is no difference in these cases.
If Nerof Gasgal is dead in my game, and I buy a book in which he is alive, I have to disregard or change that.
If Nerof Gasgal is mayor in my game, and I buy a book in which he is not there, I have to disregard or change that.
Disregarding or changing doesn't become easier or harder simply because the disparity between my gameworld and the published material has one origin or another.
Which is a change, but it isn't a retcon or a change of canon. It's a change of tone and theme. Which is an entirely different topic.
Changing the tone and theme of a setting is, in my view, not entirely different to changing canon. They are both changes that have some impact on a person's engagement with, and use of, a setting. And changing the tone of the setting is (for me, at least) much more significant than changing some minor fact of geography or history.
At the risk of being insultingly simplistic, there are two types of D&D fans: one who use it as a ruleset to run their own games, and ones who use the setting and world of D&D. Lore really is always for the second group.
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why have lore at all? Why not just have a series of suggestions and possible lore. Or leave it blank and give DMs the ultimate freedom?
Answers to all this have been given upthread. It is
work to draw maps, write histories, name NPCs, etc. Having someone else do that is a service worth paying for.
Not to mention that the people I am buying setting material from might do a better job than I would of drawing maps, writing histories, naming NPCs et.
As [MENTION=1288]Mouseferatu[/MENTION] said, this is the primary function of D&D setting material.
there are those who enjoy continuity. Why like reading lore and connecting the puzzle pieces together. Discovering secrets. It's like trivia.
People who ignore continuity can do so if it's consistent or not, but people who enjoy it want it to be consistent.
Is the function of D&D setting material to please canon fans? Or to provide material for playing the game.
If the latter, then the benefit of ignoring consistency/canon when it adds nothing is that it gives me better material for my game!
If a major detail like that is wrong... can you trust the rest of the book?
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How useful is it at your game when your players might notice a contradiction at the table? Or if major background needs to be rewritten for your campaign.
Trust it for what? And if the GM is feeding the players contradictory material, the issue seems to be with the GM, not the author of the supplement.
Who cares if the Mind Flayers have been around for only 2000 years and the gith escaped Mind Flayer slavering 10,000 years ago? Who cares about logic and consistency?
But clearly no one is going to use both those ideas in a single game. It's not hard to add an extra couple of digits to one of the dates, or knock some off the other.
you often still don't have a choice. Fairly often, you'd choose the lore that you have. With Mind Flayer lore, you're likely own the more modern version rather than the rare and more valuable 2e supplement.
And that's an issue because?
And don't force that lore into the Realms and Eberron and Dark Sun.
See, I don't see how any is being "forced" to do anything. If you don't like the 4e Realms, you just ignore it. Like when I run GH I ignore good chunks of FtA and subsequent supplements.