The "book writing" metaphor is right on the money and is neither rude nor anything except good advice for newbie DMs who don't know exactly what they're doing and try to railroad adventures with the best intentions.
It refers not most of the time, but *all* of the time to stuff like:
DM: You need to break into the castle. You know that there are secret sewer passages that can get you inside.
Players: We try to climb the walls and get in through a window!
DM: All the windows are closed. There is an open grate leading into the sewers right beside you, however.
Players: The thief lockpicks one of the windows to open it!
DM: All the windows are spellbound with locking spells far above the ability of any mage to Knock or and thief to pick. The sewer grate lies open.
Players: God, we dont wanna go in the sewers that's lame, we try to bribe the guards into letting us in.
DM: The guard is impervious to bribes, and pushes you away, in the direction of the open sewer grate which is wide open.
Players: umm... we're going to try to disguise ourselves as travelling troupe of actors to perform for the king and try to sneak in that way.
DM: Oh sure... as you look around for a disguise to buy, the ground opens up under you, and you fall into the hole. The ground closes back up after you land. You are now in the sewers. The waters carry you in the direction of the castle above.
Players: ...
Now, I agree with all the rest of your OP, but as for the book-writing metaphor, it is very apt when applied as meant to be applied.
As a DM, I love setting up really interesting beginning scenarios and lettng the players do what they will with the monsters and traps inside. But I do have a problem with endings, since I never think abotu them, and have been told a couple times that a certain quest was underwhelming because of how it ended (because I was totally just making something up at the time). It's something I definitely have to work on, but I don't think the way is by writing a whole story of how it's going to go... maybe a list of possible outcomes or something.
It refers not most of the time, but *all* of the time to stuff like:
DM: You need to break into the castle. You know that there are secret sewer passages that can get you inside.
Players: We try to climb the walls and get in through a window!
DM: All the windows are closed. There is an open grate leading into the sewers right beside you, however.
Players: The thief lockpicks one of the windows to open it!
DM: All the windows are spellbound with locking spells far above the ability of any mage to Knock or and thief to pick. The sewer grate lies open.
Players: God, we dont wanna go in the sewers that's lame, we try to bribe the guards into letting us in.
DM: The guard is impervious to bribes, and pushes you away, in the direction of the open sewer grate which is wide open.
Players: umm... we're going to try to disguise ourselves as travelling troupe of actors to perform for the king and try to sneak in that way.
DM: Oh sure... as you look around for a disguise to buy, the ground opens up under you, and you fall into the hole. The ground closes back up after you land. You are now in the sewers. The waters carry you in the direction of the castle above.
Players: ...
Now, I agree with all the rest of your OP, but as for the book-writing metaphor, it is very apt when applied as meant to be applied.
As a DM, I love setting up really interesting beginning scenarios and lettng the players do what they will with the monsters and traps inside. But I do have a problem with endings, since I never think abotu them, and have been told a couple times that a certain quest was underwhelming because of how it ended (because I was totally just making something up at the time). It's something I definitely have to work on, but I don't think the way is by writing a whole story of how it's going to go... maybe a list of possible outcomes or something.