So if I'm understanding this (clarified) explanation of dissociated powers...
... feinting in melee combat in AD&D is dissociated because it isn't something the player can choose to do. It's assumed their character is doing it --all the time, when they're in the mood, if they got bit by a feinting bug that morning-- but declaring a feint has no effect.
No, that is not a dissociated mechanic. There is no feinting mechanic, for one thing. Feinting is simply generalized into to-hit rolls.
... critical hits in D&D 3e are dissociated, because they're a product of mere probability, modified by weapon type and possibly feat choice and class ability. But not by player choice during live play. A player can declare "I'm shooting for the eyes --or any other vital spot-- but this, again has no effect.
That is not dissociated, either, since people who shoot for the eyes do not always hit them. In fact, it's safe to assume people are always shooting for the eyes, if the opportunity presents itself. Actually being able to make called shots to the eyes is more likely to be dissociated, since it's rare that a game would closely model whether or not the eyes were a reasonably available target.
... saving throws are dissociated powers aren't necessarily tied to specific character actions, and the representation of a saving throw in the game fiction is described after the fact. The order of operation is: player makes a saving throw --> die roll is evaluated --> character's action in the fiction is described.
Not dissociated. In fact, saving throws are a flat-out simulation.
So dissociated mechanics have always been around, right? So can we talk about in a more nuanced way, perhaps discussing why some are good, or at least tolerable, while others get people's dander up?
Do you understand that glossing over the very subject of discussion and considering it solved is frustrating? None of those are dissociated mechanics. It has been claimed a couple of times that dissociation is just a level of abstraction, but I do not accept that position. Something can be highly abstracted but still completely immersive.
Player: We go back to the inn.
GM: Twenty minutes later, you arrive at the inn.
Another example:
GM: There are still two guards by the door.
Player: Are they the same guards from before?
GM: Yes.
Traveling a couple of miles, or recognizing another person on sight, are both considerable and complex tasks. But they aren't exactly really challenging, most of the time, so it's worthwhile to simply abstract the tasks. There is no really justifiable reason to make the players play out a twenty minute walk in real time, or to make the players roll a series of Spot/Perception checks in order to determine something that is easily determined.