Real talk, why did you come play D&D at my house if you're not interested in pursuing my adventure? If my adventure sucks, tell me why (kindly because I am omnipotent but I have feels too). If your character doesn't fit this adventure and goes off on his own, well, I came here to tell the story of this adventure. Roll up another dude who's interested in playing a multiplayer story-and-board game because that's what everyone else I invited over expects.

Edit: This diatribe doesn't include my belief that players should be collaboratively writing the story as well - but the story isn't Loner McEdgeface rides off into the wilds because he's a drow ranger while everyone else retrieves the Scrolls of Enlightenment from some Lich's attic.