I meant narrative games.
But the same is true of all games--the GM probably shouldn't put stuff in the players don't know about yet, except, perhaps, foreshadowing (or maybe infodumps). But at the same time, the GM, even when writing a trad game adventure ahead of time, is going to know what the adventure's goal is, and thus could possibly be influenced by it when writing the earlier parts of the adventure. They know who the BBEG is, what sort of obstacles lie in wait, and so forth.
That being said it's usually considered a
good thing to hint at what's to come in both types of games. In narrative games, that's usually a GM move ("hint at future badness") and in tradgames, so it doesn't feel like an @$$-pull or like all the clues were nothing but red herrings.
But at the same time, the GM, even when writing a trad game adventure ahead of time, is going to know what the adventure's goal is, and thus could possibly be influenced by it when writing the earlier parts of the adventure. They know who the BBEG is, what sort of obstacles lie in wait, and so forth.
This is not a narrative game problem. It's a GM problem. I've had a few occasions where my current D&D DM--great at intricate plots and making NPCs feel real, and who to the best of my knowledge has
only run D&D5e and has minimal experience with narrative games--has admitted they'd pulled their punches to keep from a TPK, which yes, highly annoyed me.
(Meanwhile, I was once jokingly berated for
not doing the same thing: "You know who
else ran traps exactly as they're written in the adventure?
The nazis, that's who. ...I'm a cleric, I can Godwin if I want to." Nobody actually died due to the traps, but they took a bunch of damage.)
@The Firebird's problem, I'd wager, was
not because he was running a narrative game but because he was
inexperienced with running narrative games. A GM that is experienced in a particular game will know how to run it. He wasn't, so he didn't know what to do with those ideas and thoughts.