You must have been squinting a lot reading some of those stories, then.I think it pretty much did, and it was pretty much the same as the movies', that time travel just creates alternate timelines.
While they ostensibly take place in a shared setting, Agents of SHIELD and Endgame are not the same work of fiction. As with the comics, different hands.It is incumbent on the creators of a work of fiction to keep it consistent within itself. It doesn't have to be consistent with real-world rules, but a failure to keep it consistent with its own internal rules is a flaw in the construction.
The first time I personally remember the "divergent timeline" idea being used was in Byrne's FF run in the 80s. Now maybe it's been retconned since then that all time travel works that way, but it certainly wasn't meant to be a part of major time travel stories prior to that, like Englehart's Immortus storyline.