To me some posters are raising a reasonable concern about an acute category of GM or game designer prep being given standing in the fiction prior to becoming known to players, which is when the prepared element seems like one that couldn't be needed unless players are to act in a certain way. Which seems to make assumptions about or override their agency.
Whether giving those unused elements standing in the fiction is valid or not depends on the playstyle agreed upon before play began.
Then, I wonder at calling this a "concern", insofar as games that intend to preserve player agency in that particular form already have that preservation baked into their design - if the GM follows the game rules as stated, they
won't be giving those possibly unused items standing in the fiction, and may not even be generating ideas for those possibilities ahead of time.
To wit - when you agree to play bog-standard D&D, there is no "concern", as there's no promise to the players that all elements of the fiction will match their particular agendas.
It is pretty much only in the edge case of agreeing to a playstyle that the rules are not specifically designed for, that this will be a "concern". And, while the choice to do that is a valid one, the GM who was part of that choice is kind of on the hook for worrying about the concern. Folks on EN World should not be expected to answer for it. Maybe go ask that GM why they are choosing D&D for that approach to play, instead of Dungeon World, Blades in the Dark, or some other game that is closer to the right tool for the job.
Redundantly preparing a wide range of such elements could feel dissatisfying as surely it's impossible to anticipate every unfolding line of play.
Well, for one thing, prep-heavy games tend to attract GMs who find preparation itself to be part of the fun for them. Telling them to do less of it is telling them to have less fun. That's not going to get you far.
For another thing, GMs don't have to anticipate
every unfolding line of play.
Indeed, for me professionally, there's a valid saying: "The Plan is not the valuable thing - the value is in the
act of planning. " Having gone through the act of planning, you have reviewed the situation in some detail, and have considered how the pieces of the situation inter-relate, and have them recently in mind. Then, when things go
against the plan, you are in a far better position to adjust to the unfolding situation than if you didn't plan at all. Having planned a couple of likely scenarios, the GM is more likely to be able to come up with one to cover a third direction not yet considered on the fly.