I think there are quite a few presumptions outside of assuming relevant context that are problematic in [MENTION=42582]pemerton[/MENTION]'s argument. One that immediately springs to mind is the presumption that players will be more invested when the context is something they have a hand in. This assumes the players will be more invested in character connections vs discovery or exploration of the unknown...and for some players this just isn't true. I wouldn't argue that players participating in a West Marches campaign are any less invested or engaged around discovery and exploration of the world than a player who has had a hand in creating some part of the world and is engaged... it really again boils down to preferred playstyle, game type, etc... Yet [MENTION=42582]pemerton[/MENTION] seems to only be considering those with his preferred style and type of game as opposed to the hobby as a whole.
I do agree with your point quite readily that players have different preferences in terms of engagement.
Though pemerton may indeed have the presumption in the bold, I'm not sure if his argument in this thread hinges on it. Pemerton's initial thesis in the OP, for example, is silent about whether the fiction that the players engage through play is something that they have an
a priori hand in creating. When pemerton speaks on the emphasis in RPGs "on participation in the creation of a fiction that is structured through distinct player and GM roles," this seems more about the general process of creating fiction through play: i.e., when you play a TTRPG, the process of play creates new fiction. A West Marches style game would likewise create new fiction as the players decide which piece of fiction to engage and in the process generate new fiction through their collective choices. IMHO, a West Marches style game is predicated on the idea that players will "engage with and build on this fiction in ways that display the player's view of the fiction" since WM games require that players pro-actively engage the fiction, even if that only entails peeling back the fog-of-war on the map.
In my reading of the OP, pemerton does not believe that the "literary quality" (i.e. wordcraft) for the narration of situations performed by GMs (to which players respond) matters, or at least should be regarded as a secondary nature. Instead, pemerton appears to be arguing that what matters most is that the stakes of the fiction are understood such that players can properly perform their duties as players who participate in the fiction. And implicit in this argument is the idea that attempting a high literary quality of GM narration can risk relegating the players to function more as an "audience to a performance" by the GM rather than themselves being the primary participants of the fiction. I'm not necessarily sure if pemerton would word it in this way, but it's possible that his point here could be understood as a fear of when GM narration happens
at the players for the sake of wordcraft itself rather than
for the players to contextualize their participation in the fiction.
In sum: the contextualization of player choice within the fiction of TTRPG play - presuming (not so radically at all) that TTRPG gameplay is driven primarily by player-character choices - matters more than the quality of the narrated wordcraft of the fiction that a GM may supply to players.
