It is striking, to me, just how difficult a lot of discussion of RPGs makes it to express simple points like the one I have quoted.Okay, who's a human who is actually thinking? The player. Are they better at hindsight then foresight? Yes. Flashback mechanics fit what players are better at better than none.
Who's a "human being in a heist fiction"? The characters. Are the characters relying on hindsight in their adventures? No. The flashback are things that happened previously for the character.
In other words, flashbacks meet all of your requirements better than no flashback mechanism.
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Nothing is conjured into the gameworld after the fact. That's who point of it being a flashback. It was done previously. It just was done off camera without those outside the gameworld, such as the DM or players knowing about it. But in the gameworld, it happened before. And it needs to follow all the rules and sense of the gameworld.
RPGing is shared fiction. That fiction gets authored at all sorts of times - some as prep, some during play. And the temporality of that fiction is in all sorts of relationships to the "now" of the PCs: when the GM decides to tell the players about a castle their PCs sees, that establishes that, prior to "now", someone built the castle; when a player decides to write "10' pole" on their equipment list that establishes that, prior to "now", there was a tree and a logger and a maker of timber wares; etc.
Suppose, in a game of D&D, that the GM tells the players that their PCs see the castle, and a player says, "Can I recognise who might have built it?" And the GM asks, "How would you know?" And the player replies, "Well, my PC has training in History and the Soldier background, so I know a fair bit about castles and who builds them." So the GM replies, "Fair enough. Make a roll on INT (History) against DC 15". The player rolls, and succeeds, and the GM tells them what the know and recognise about this castle.
That seems to me a completely unremarkable episode of D&D play. It's also a flashback - it establishes that sometime in the past, the PC did or learned something that is relevant to what they do or think or recognise "now".
The difference with a BitD Flashback, as far as I can see, is that the BitD version more easily extends across a wider range of activities, a wider range of upshots (eg not just remembering things you did, but still having the tangible benefits like the rope you remember you brought along), and more immediate salience to the problem that the PCs are currently confronted by.
Those differences might be interesting to talk about, but none of them pertains to anything to do with the temporality of events in the fiction, or of the temporality of authorship at the table.