This is missing the point.I think the best way to address that is to ask, what character from such a system can't be played identically in a D&D type system (assuming same overall setting etc).
Since D&D largely leaves personality free form, then all the personalities allowable in exalted are available in D&D and all the ones not allowable in it are as well.
One may as well ask, What story can't D&D produce? Well, if the players and the GM all get together and agree on it then you can play out Casablanca in D&D, can't you? (That was [MENTION=16586]Campbell[/MENTION]'s point about consensus.) But the current topic of discussion is how that might be done, and what sort of play experience might be involved.
The example of Exalted, for instance, was not about what personalities can be played. It was about how personality might put under pressure, and perhaps change. And the play experience that results from that.
Anyways, one potential challenge for the player is determining if that is a persuasive argument to their PC.
You're not learning it. You're deciding it - as seems evident in your use of the verb determining in the first quote.When the choice is between two opposed goals/personality traits/etc then you are most certainly being confronted with something new or unexpected about your PC. You are learning which goal/personality trait/etc is more defining (or at least more defining in this moment).
If the player is playing in character then the only reason the determination of what his character would do would be difficult for him is if the attempt framed the situation to the PC such that it put two motivations/traits/etc in opposition. That then becomes a defining moment of the PC's character.
Maybe it's a hard decision, but it's a decision, not a discovery. As I said, I can't see how this puts the least bit of pressure on the player's conception of his/her PC's character. (I guess it could if the player had said of his PC both I am chaste and I will do whatever it takes to preserve the kingdome. But the conflict there is so obvious and so shallow that I think we can discount it as a working example.)
Contrast that with the example I posted of the paladin: he learns he is a killer. Or the examples of Duel of Wits, or Exalted social conflict: the PC (and player) learn that the character is capable of being persuaded in such-and-such a fashion.
Those are not choices made by the player; they're the results of putting things at risk, and then losing them. (This is, roughly, [MENTION=16814]Ovinomancer[/MENTION]'s definition of a challenge.)
But in the examples you provide this "internal struggle" is all just colour - like in D&D combat if the GM narrates the hp loss as a blow to the arm or a blow to the leg. It doesn't actually matter to resolution, or to the unfolding of the fiction.For the PC, the persuasion attempt is a challenge only if it makes the PC stop a moment and debate back and forth on what the right course of action is.
Often times, when the player is struggling to determine whether the NPC persuaded their PC, it's because the PC is having an internal struggle as well over what they should do.
Contrast the paladin example: the killing isn't epiphenomenal. It's an actual thing that has occurred in the fiction, which refutes the paladin's self-conception (I'm not a killer) which has been held up until that point. Similarly for the outcome of a Duel of Wits.
Which goes back to the point about play experience. Thinking really hard about what you want your character to do, and then choosing it, is not the same play experience as being forced to recognise that your character is not who you thought they were. And this is where the issue of familiarity with other systems and other techniques comes in. Your posts in this thread give the impression that your RPG experience does not extend far beyond AD&D 2nd ed and similar sorts of systems (eg a fairly common approach to 3E and 5e D&D; maybe a bit of GURPS or HERO or even DragonQuest played in a similar style; but not a lot else).
If that impression is a mistaken one than I apologise - but I certainly don't get the feel that you've played (say) HeroWars/Quest, or DitV, or Burning Wheel, or any PbtA game, or even AD&D Oriental Adventures with the GM pushing hard on the honour and family systems that are part of that.