I think the confusion lies in what is meant by the options here. Like sure, the players of course can choose to do anything and the GM preps for that, but the player choices are still happening within the GM curated world, so in that sense their options are limited.
How so? I mean, by the larger trappings of the setting? Sure. I don't think anyone is saying that players have unlimited authority to do whatever they want. But that depends on a lot of things.
In my experience, when a GM runs a game like this, they're the kind of GMs who have left plenty of room for things to be added to the setting without it causing a major issue. I'm playing in a PBP here on the forums, run by
@Manbearcat and the other players are
@AbdulAlhazred and
@Grendel_Khan. One of the things
@Manbearcat asked us for was a short list of quests we'd like for our characters. One major quest and two minor ones.
My character is a kind of Batman-like vigilante character, so my quests are all going to be something suitable to that. Some criminals to track down. I selected a figure from within the setting as the focus of my major quest. He's a shady lord who seems connected to lots of crime in the area. My other quests will be similar, but I'll be creating them largely whole cloth... NPCs, factions, and so on.
As i said before. If players are forced to choose only A, B, or C then i would agree. But the truth is, they never are forced to only choose A, B or C. They can always say 'none of the above' and ask for additional choices or say 'none of the above' and make their own suggestion.
The problem seems to me to be the insistence that the choices are meant to be exhaustive rather than inspirational.
In my experience, as both player and GM, this is often not the case. Very often, the players are expected to engage with the GM's material. You don't have to look far to find plenty of examples of this. All of WotC's published adventures rely on this. Many GMs craft their own versions of this type of game.
I mean, I've played in these games plenty of times. I've run these games plenty of times. And there's nothing wrong with them. They produce a perfectly fun type of play.
And I'm saying that's always an option in every rpg ever. If the players don't choose to do that then it's because they were happy with one of the non-exhaustive options presented. And if so then I can't understand why that's not viewed as the player driving the focus of the fiction. They made the decision to go with it when they could have chosen nearly anything else.
So if a GM buys Tomb of Annihilation and reads through it enough to run it competently, and then in, say, session two, the players decide they're not interested in exploring the jungles of Chult to find the Tomb and try and solve the death curse plaguing the land... that GM is just going to shrug and say "oh, okay... what do you guys want to do?"
Now, I'm not saying that can't be possible... but I would say that it definitely is not going to be the common response. Some folks are going to be annoyed by the time, effort, and money they put into preparing that game only to have the players not engage. And rightfully so.
But maybe more importantly I view the game as a collaborative effort. Neither the player nor DM solely drives the focus of play. It takes both of them agreeing for the game to be played and to continue to be played.
So what examples do you have from play? What anecdotes can you share of players generating fiction in your games and how did it go?
You seem to almost be challenging the premise while also claiming that it's true for you or even for every game.