So, if I only envisage a game where the GM is the origin of all fiction and defines the entire state of the world outside my character's skin, and the overall focus of play, the possible plots and participants, locations, etc.; where the focus of play is ON those things, exploring them, manipulating them, etc. then the only kind of expression that said player CAN articulate is one similar to what you have described. That is they won't articulate a divergence of agenda into the realm of controlling the focus of play because they simply have not experienced the possibility of that kind of game. VERY rarely people will escape from those sorts of mental constraints! I mean,
@pemerton has shown examples from 1977 Traveller of a part of the rules which envisages a kind of player-directed focus in one small area (Streetwise skill use), and I'm sure we can describe others (I think its fair to cite the game 'Toon' as being pretty open to this kind of thing). I remember we used to play a game called Gangster! where we hit on the idea of the gangsters pretty much just inventing criminal enterprises and describing how they worked, making up corrupt cops and whatever else was required to describe it. That was probably not the way the game was written, but we came up with that, though oddly we never thought to apply similar techniques to, say, D&D.
I have played different paradigms over the years. From old-school to challenge-based to LARP'ing even to GM-less ones. And narrative miniature games as well (which are interestingly almost always without a GM and despite the execution of games being wildly more focused on mechanics than RPGs, the narrative is decided upon as a shared activity entirely, and thus are strongly narrativist even if the games linking the story are the opposite). I generally don't experience problems of agency myself - outside of bad groups - and that's really a different kind of agency ("how can I get out of this the quickest without ruining the fun for the rest of the table?"). But when I read about people who complain about agency it tends to fall into three categories:
1) People looking for a new system (or to modify their existing system) to support a certain level of agency. I've also found that harmonious groups can adapt systems to match, but I also recognize that picking a system with better support can create enthusiasm and bring more smooth gameplay. So I understand why people do this, and I think it's great that different system exists and that people are constantly experimenting with creating new ones.
2) "Flawed" players and/or GMs. This is kind of a tough one to go into without writing a very long post - but some people simply create problems for others at their table. This can manifest as (real or perceived) agency-related problems.
3) Mismatched expectations. If the table don't agree on the social contract, then a system isn't going to fix those problems. It can make the problems worse. This could be a GM doing narrative rubber-banding when the players expect narrative agency - no system can fix that. It could be players who want to focus on mechanical challenges and puzzle, but the GM and/or other players focus on other aspects of the game.
People who are well-informed about systems, who know what they want - they're not going to have problems with player agency. A player who hates the concept illusionist-based techniques shouldn't play with a GM who uses those techniques.
For me the interesting discussion isn't so much about academic discussions about defining agency in the context of different systems. I recognize the value of that discourse, but I don't think it's the interesting discussion to have. I think the interesting one is how to deal with problem tables. Especially that subset that can actually be fixed. The ones who who know what they like and how to get it are not interesting - nor are the ones that cannot be fixed in other ways than removing specific individuals from them. The interesting ones are the ones where there is a compromise to be made, a technique to be learned - or perhaps a system change to be made.
Some groups will benefit from switching to a narrativist system as the solution to their woes. But I suspect that for most it's actually more about learning how to be a better GM and a better player. That's about preparation, improvisation and/or interaction. Hack and slash is still the most common style of play - and I think the problem is very often that moving beyond that is hard. Giving players agency - if they do not want to switch to a narrativist system - but want the agency in the context of a different system is hard.
Yeah, I guess that's really it - I think the interesting challenge is how to handle groups that do not want to fully share the burden of narrative agency - but that still want player agency. How can GMs provide that? How can players do that? What kind of limited sharing of narrative authority can help affect narrative agency.
For me, I don't like rules-based shared narrative agency. I guess it does to me (as player or GM) what illusionism does for some others. I want shared narrative agency - absolutely. But I want it based on informal means. By the GM picking up on player cues. By players talking to them GM between session (or even passing messages/notes to the GM). Sometimes it can be done by creative "initiative" (ie players making factual statements as if they were the GM - "I know this person - we went to the same school - I recognize her and .. etc etc"). But such techniques require very harmonious groups. That's my preferred situation. Fully shared narrative authority - but without making it part of the system. And with the GM having the ultimate burden of keeping things fun and interesting. But everyone is different.
I don't think my preference is low-agency because I like the shared narrative agency to be manifested without system support. But I do recognize that systems can support and provide agency in different ways and at different levels. Absolutely. But I think helping groups, that like me, don't enjoy having player narrative authority codified, is a valid subject of interest. As is how to make the most of narrativist systems - because I can enjoy those, even if I don't prefer them as a baseline. It's possible to enjoy more than one system and one style. Which is where my earlier comment of railroading came from. I like it sometimes. Either as an element in an experience that is full of agency - or even as the main style. I don't think there is any gain to only enjoying one style of play (just like I read different kinds of literature and listen to different kinds of music). But sure, I have a preference - and that's not railroading.