I realize this, and I'm not refuting that. But most science fiction also allows characters to change the past or future. The timeline has already occured, future, past and present are relative, everything already has happened.
The best use of time is "The Watchmen". Therefore we are not changing the outcome of our timeline regardless of what we become aware of or do, because if we are aware it is only because history dictates that we become aware at that point. Nothing happens "regardless" of time.
That said, most science fiction writers are working with a pliable, workable frame. A fiction. They're not working within the realm of a realistic and probable representation of actual time control. To further this confusion, think about the common elements or themes associated with time travel or time control...
A.) In the future something bad happens and characters go back in time to stop it from occuring.
B.)Someone from the present/future goes into the past and changes things to alter the future.
Neither situation could happen because the story would start originally with the future already changed. How could a separate past lead up to a future that leads to an alternate past?
X-is our current status
Y-is the future
z-is the past
z=X, x=y, y=y-z? y-z=2x Yet somehow 2x=x? No.