FrogReaver
The most respectful and polite poster ever
To a point.
In a truly linear adventure, designed as one unavoidable room after the next like a string of beads*, there's only ever three exploration choices for the PCs: go ahead, go back, or stay put where they are. In that respect it's the same as a railroad, as the driver of a train on a track also has only those three choices: the train simply can't go anywhere else.
* - some of the old TSR tournament modules are very much designed this way.
I wouldn’t even call that a railroad if that’s what the players agreed to.
They could have started and stopped with just "The events of the story shouldn't be predetermined; the actions of the players' characters have to matter." and it would be great advice.
Adding that preamble about the players being co-authors doesn't help anyone IMO.
At a minimum character backstory is authoring that players do. So I can’t really disagree with the statement, but it could easily be interpreted much more broadly and I would have some issues with some of those more broad interpretations.