I'm not incredulous about that. Stories, when told well, evoke emotions.
But they are not normally the emotions of a protagonist. They are typically sympathetic or aesthetic emotions of various sorts
First, sympathetic emotions often reflect the emotions of the character. But yeah, when I am immersed into the viewpoint of the chracter, when I have internalised their persona, then yeah, I do feel the feelings of the character, at least to some degree. And to me such inhabitation is kinda the main point of playing RPGs. And I most definitely do not need or want or need rules for that.
Sure. A lot of people also can't ride unicycles - I mean, I know that I can't! (Even though I'm a pretty experienced cyclist.)
But I don't know what that is supposed to tell us about player agency.
Rules dictating the emotions of the character limit the player's agency to generate such feelings via the their internal model of the character. Seems pretty straightforward.
I don't really know what this means.
Upthread, you referred to "player agency to solve a mystery". Where the mystery is not an actual mystery - the players aren't actually detectives - but a fictional mystery, like a whodunnit or similar.
If this is a species of player agency, then we could also talk about player agency to view a map, or draw a map. Or player agency to solve a riddle. Or player agency do any number of other things that might be associated with the sort of fiction generated by RPGing.
I'm sure one indeed could. And if a player felt agency regarding such matters important to them, yet the game would not allow it, then it would be a problem for them.
And of course the mystery is not real mystery in a sense that the events are physically real, but it is real mystery in sense that there are facts that exist about it, that can be found and deduced. That is obviously different than the players inventing clues and events that in the end resemble a mystery story.
Games have structures and limitations that enable one sort of play but which might simultaneously limit another. As another example. some games might have rules which allow resolving combats swiftly, perhaps with one roll. This might be better for certain sort of drama, but it simultaneously disallows the player agency to affect the outcome of the fight via tactical skills.
When I think about player agency in the context of RPGing, the sort of agency that I find salient is agency in respect of the shared fiction - and, given the asymmetric game roles that are typical in RPGing, for a player that normally means agency to establish what sorts of goals can be meaningfully pursued by my PC as a protagonist, and what sorts of opposition will occur, and thus what is at stake for my PC in play. That's pretty broad, and thus encompasses quite a range of RPGing, but there is some stuff that it excludes - namely, GM-driven play where the GM determines the goals (eg via "adventure hooks") and/or the opposition (the poster-child for this is the quest-giver who is really the villain - who would ever have anticipated such a shocking turn of events?!?! - but there are many less heavy-handed ways in which GMs decide the opposition) and/or the stakes (most often, at least it seems to me, GM's decide this by reading it from, or extrapolating it from, their notes).
I agree that agency of setting goals is important, but it is not only sort of agency a player can have in the game, nor it is something everyone cares about. For example, to some it might be more important to have agency to set means and tactics for achieving said goals.
Now setting the opposition, that seems far more contentious. Of course setting goals to some degree determines the opposition, but not fully and not always.
And as for your cliché example what some people in this thread have argued for, and I have vehemently argued against, is that in such a situation the "villain quest giver" should be able to compel via social mechanics the PCs to believe he's their ally and even compel the them to do his bidding. To me that would seriously harm the player agency of setting their own goals.
The RPGs that I enjoy the most don't limit player agency of this sort, and others that I enjoy generally don't limit it much - eg I've found that it is not that hard to use Classic Traveller's patron generation system and random encounter system in a way that doesn't involve the GM unilaterally deciding the opposition and the stakes.
Perhaps. But to me some of your examples go against this. For example if in an Arthurian milieu a NPC can compel the PC to fall in love with them against the player's wishes, then to me this would limit the player's agency for setting their character's goals, at least if we take this feeling and the genre conventions seriously.
This I don't really get. A typical feature of good stories is that the events of the story pertain to, and reflect upon, the protagonist. This doesn't make stories contrived (except in the obvious sense that they are deliberately authored). It just means that the stories are about something and someone.
When Sherlock Holmes or Hercule Poirot solve a case, then it of course to certain degree is about the character. They do it in their own style. Like various Star Trek captains would probably solve similar situations differently as they're different sort of people. But the focus of the story still is not always, or even often about the personal issues of these characters. It is about the situation and solving the problem.