your entire preferred play experience has been 'a world created by people who are also subjects of a story about them'
This is just wrong. The people who create the world are me and my friends. The subjects of those stories are Thurgon, Aramina, Aedhros, Alicia and othes, all of whom are purely imaginary.
your character thinks 'i wonder if there are spellbooks here' and looks for them
Yes. This is an event that occurs in the fiction. It is not unusual for people to wonder about what they might find in a place, especially a mysterious one like Evard's tower.
you as a player roll the dice
Yes. Players in games do things - roll dice, draw and play cards, move pieces etc as part of game play. In RPGing, rolling dice is especially common as part of resolving an action declaration like "I look for spellbooks".
to see if reality indulges their desire to find spellbooks in the place they are
This is a very bizarre thing to say - it's like saying that, in D&D combat, I roll a d20 to see if reality indulges my character's desire to wound the Orc!
I think a far less stilted way of putting the point is this: the dice are rolled to see if the declared action succeeds, where
success is defined by intent + task (in this case, task =
I'm looking, and intent =
for spellbooks).
the fact you are rolling to see if they are there or not, not just if you find them or not, means you are defining the world, means you are creating the possibility that spellbooks exist in that location
I discussed this quite a way upthread. The actual process is this: my action declaration gives rise to the question,
Does the fiction include Thurgon finding spellbooks in Evard's tower? This is a perfectly reasonable thing to wonder, just as one might wonder, when playing D&D, whether the fiction includes your PC stabbing an Orc.
The rules of the game did not permit anyone to unilaterally decide the answer to that question about Thurgon finding spellbooks. The rules required dice to be rolled: everyone has agreed that, on one result (success), they will make
Thurgon finds spellbooks part of the shared fiction; on the other result (failure), they will make the adverse consequence that the GM narrates part of the shared fiction.
Of course, "Thurgon finds spellbooks" entails "Spellbooks exist". Likewise, if the roll fails and so the GM narrates "You find letters to Daddy Evard from child Xanthippe", that entails that those letters exist. It's a deliberate feature of the game that the action resolution process permits elements of the fiction to be generated by way of entailment from the narrations of both success and failure on checks.
The earliest RPG I know of to fully embrace this method is Classic Traveller (1977), although I suspect that Arneson and Gygax probably used it from the start, as it is obviously a very powerful technique in a game of shared imagination.
as someone who the story is being told about.
This is just wrong. I, a person who participated in the process of establishing the content of the shared fiction, am not someone about whom the story is being told. Just in case there was any doubt, I am not Thurgon. He is purely imaginary.