OK. I don't quite see how this relates to playing a RPG.
That's why I chose an example - being inspired or prompted to write a poem - that seemed to more closely resemble the idea of being inspired or prompted to write setting lore.
Huh? So do your players add non-cosmetic scenery and consequential NPCs?
Collaboration just means that we're working together for an end result we all want. In a game, our goal is to play an enjoyable game. In the case of web design? The person doing to basic layout may have ideas that we tweak and adjust when we actually go to write the HTML. On a pretty regular basis one of the developers will have a better idea on how to do something and discuss it with the designer. There is a lot of back and forth. But what makes it all work? It's the developers actually doing the work (again, collaboratively) to make the web page and back end. Without them you don't have a website. Without players, you don't have a campaign.
Perhaps a better example would be a play. The director, the construction coordinator (craftsmen making the stage and props) along with the actors are all collaborating, correct? The director doesn't act, the actors don't build the stage or the props but they can all provide feedback back and forth to each other. As DM I take the role of the director and construction coordinator to set the stage. But that doesn't mean the actors don't have any influence because this is a highly improv play where they are not limited to a script. So I have to change the stage based on their actions, come up with new direction based on their choices.
So in this highly improv play of ours, the director is there to give general direction and build the set. But what the actors do and say is largely up to them. The actors in my play are not following my script, they are just reacting to what's on stage and the prompts that I provide as a director. For that matter I'm rebuilding the set on a regular basis based on their choices as well.
There would be no ongoing campaign without players. In my games the players constantly influence the direction of the campaign. We work together outside of the game if the player has some goal or desire that I haven't introduced for them to pursue. They aren't adding lore outside of what they do, but otherwise they are in control the flow and direction of play. I may set up props and optional goals but they decide what to interact with. I don't see how that isn't collaborative, how we are not working together.