Lanefan
Victoria Rules
The DM tells a story in order to set up the - to use your term - scenario.Actually, here’s where you’re mixing this up:
What the DM has done by relating stories about events in the campaign setting is to aid in player immersion of the Game Setting, and to set up several Scenarios or "events" that the Players can interact with.
“Scenarios are long-term tests comprised of several tasks. They are usually explicitly stated to a player, whether through story or as formal win conditions.”
Just because the DM uses story as a means to convey information and Scenarios to PC’s as one part of his many roles in running a campaign setting for the players to interact with; that does not mean that the GM and Players are engaging in story-writing as a group.
Then the players play through that scenario in whatever manner they see fit.
And in so doing they metaphorically* write the story...
* - and sometimes literally, if the GM and-or one or more players are taking notes even as play goes on.
...that is later recouted verbally, or put in a game log, or whatever.There is no “or” you can’t have it both ways: because words have definitions.
During a game session; RPG groups are not writing a story, they are playing the game.
Story (noun)
1. An account of imaginary or real people and events told for entertainment.
2. An account of past events in someone's life or in the evolution of something.
While RPG’s can be immersive during gameplay, By the very definition of the word, the “story” part for the RPG group will only occur as the DM or players recount events from the session or campaign, in spoken or written form.
The difference in an RPG is that the participants are both creating and telling the story at the same time.