It seems that the writers and directors of Avengers: Endgame disagree about the nature of the
in the film.
At the end of the film,
Steve Rogers "returns" the Infinity Stones to the various points they were retrieved from.
Under the interpretation of the writers, i.e.
removing an Infinity Stone is the only thing that creates a (persistent?) branched timeline
the motivation to do this at the end of the film makes some sense - these
branches could be unnatural/damaging to reality, and bringing the Stones back to them stops them existing or re-integrates them with the prime timeline somehow.
However, under the interpretation of the directors, i.e.
any change to the past creates a branched timeline
the motivation to do this makes a lot less sense.
If Steve "returns" a Stone to one of these timelines, he's not really "returning" it, just creating a new timeline where he has put it back, while the timeline where he hasn't continues to exist.
So - under the directors' interpretation of the
time travel, why do Steve/the Avengers care about returning the Stones when doing so will just create more branched timelines rather than "fixing" the timelines they've previously created?