Honestly, I wonder why so many people use videogames as the great example of linear storylines? Of all types of media, videogames come closest of all things to the flexibility of a good DM. In terms of ability to deal with multiple choices, the best of videogames surpass or equal many human DMs. I won't say they surpass all DMs or scenerios, but there are reasons that this difference isn't terribly big.
To argue my point, I will use Way of the Samurai, an exceptional game for this type of thing, as my example.
In the opening scene of Way of the Samurai, the player is dumped right into an area, where there is a group of thugs kidnapping a young woman just out of sight. The first thing most people would think of is to simply walk over and save the woman, and that would be the only option in a railroaded D&D game or a linear videogame. But here, there are several options, and several ways for the scene to play out. First, there is the very simple option of walking by the scene, ignoring the girl's pleas for help, and choosing from two different paths. Second, you can just draw your sword and attack the thugs. Third, you can go and speak to them, and choose between ignoring them, commanding them to let the girl go, or asking to join them. If you get into battle with them, you can try to kill your foe, demand his surrender, surrender to him, or just die. If you beat him, you can accept his surrender or threaten to kill him. And depending on what you do, you will either just wander until you reach the lord's compound, get invited to the girl's restraunt, or get tied to some railroad tracks, and the method you go about doing this can affect choices later on. This scene can radically affect which of the three major factions you end up working with in the game.
Not many DMs could handle this many significant choices (chatting about the weather does not count as a plot-significant choice) for a single scene very easily, and I bet there are some who would not be prepared for every possibility. Further, I would argue that there simply are not any interesting possibilities for dealing with this scene that the game does not allow, other than maybe giving the player the chance to make a dramatic monologue and then commit seppuku right on the bridge (which makes a better movie than a game, really). The scene itself only has so many options, and I challenge people to think of something to happen within this scene other than what is already covered, without resorting to unnecessary intervention from an NPC.
If you ask me, more problems are created when the players or the DM (especially the DM) think of a game like a book or movie than a video-game mentality creates.
