So, I was reading a book on world building for fantasy & sci-fi authors and I noticed an interesting point that I thought goes to what I am saying.
"Don't think that you will be including every ounce of what you have worked on. You won't. You shouldn't. I know. I know. You worked hard on it but it wasn't wasted even if it never makes it into your book. It helped you to understand you world, so that you can write about it in an informed, attached, and immersive way. So that you can make it all the more real for your readers" -- Angeline Trevena in the book "From Sanctity to Sorcery, An Author's Guide to Building Belief Structures"
In my style of roleplaying, this point is important. When a DM inevitably has to improv some detail of his world, he acts from a vast and detailed knowledge of that world and thus does a better job. So even the parts the PCs never encounter is still useful stuff. It will inform NPC actions and reactions. It will add to the verisimilitude.
This really boils down to preference and comfort level on the part of the GM. Having a "vast and detailed knowledge" of a fictional world does not in and of itself enhance verisimilitude. It may for a specific GM, and that is fine.
But for others, it can be the opposite. Being free to establish details as needed or desired rather than as predetermined, or as how they may be shaped by predetermined events, can also add to verisimilitude.
It really just boils down to what works for the GM and players. I used to think that I needed to have as much information as possible to do the job of a GM and that the world would seem made up if I didn't do all that work beforehand. But then I realized that running an RPG is not the same as writing a novel, and that when it comes to the moment of play, a detail that is made up on the spot is very often just as good as one that is prepared ahead of time.
The question really is about all that time spent preparing and if memorizing a vast and detailed knowledge of a fictional setting is the best way to spend that time.
Whether your position has moderated, or whether it's the wording, I find this much less objectionable (as in almost not at all) than your prior way of putting it, which A) focused on the GM's notes and B) at least seemed to imply that finding out what was in the GM's notes was almost the entirety of play.
EDIT: And I know exactly why that other phrasing bothered me so greatly: It sounds an awful lot like playing through an AP-style campaign, where the point--the only reason for play the style really supports--is to find out where the AP's story goes. Nothing any character brings to the game matters at all.
I loathe AP-style play, as a player. Even shorter published adventures intended as one-shots almost inevitably get on my nerves by the end. I make a concerted effort not to run an AP-style campaign--that's most of why I don't prep more than the current session.
Is this not objectionable to those who enjoy AP style play? Which, based on trends, would seem to be a significant amount of people who participate in the hobby.
Don't get me wrong.....it's fine that you don't enjoy that style of play. But do you think you should have to pretend it appeals to you because there are people who do enjoy it? Should you not describe that style in a way that seems accurate to you?
I've played plenty of AP games. I've run them, too. They absolutely can be fun. I don't take offense that you have criticisms of that play style, nor do I think your criticisms are without merit. I am able to look at that kind of game and see what is actually happening, and then approach the discussion accordingly. And if we're going to discuss that style, I can do so without you needing to tip toe around my feelings.
I honestly think that a lot of the conflict in this discussion is that "learning what's in the GM's notes" is a pretty accurate description of any RPG that has the GM as the primary source of the fiction. I mean, how could it not be? It's kind of baked in, no?
I don't think it is diminishing. I think it is one that can be used to equivocate and one that tends to get you lost in the metaphor of fiction (I'd rather get lost in the metaphor of living world

)
The idea that the term "fiction" which simply means "make believe" and which absolutely applies to what happens in an RPG, could somehow be seen as a more nebulous term than "living world" is part of why I struggle with your view. Fiction is not a metaphor. It's literally what's happening when we play. We are making believe.
You point out a lot how you do not like equivocation, and that's understandable, but then you prefer vague words over specific ones.
Fiction works perfectly. From what I can see, it's the fear that gaming is about "making a story" which is the source of dislike of the term fiction. But fiction and story are not exact synonyms.