Because nothing fits better with a progressive technological utopian vision of the future, than good old-fashioned fatalism?.
You may be overthinking it. It was mostly just a plot contrivance to give the audience what it expected: the familiar cast of TOS, back together again. I was just pointing out that the time-stream fixing itself is a standard plot device in classic SF, dating back to Amazing
probably. It may be a cheat, but it's one time-travel and parallel universe stories have been using for decades. Kind of like "universal translators" or aliens who conveniently speak English.
Plus, as a rule, I don't judge STAR TREK movies on whether they adhere to some abstract, ideological agenda. Telling a good story is at least equally as important as staying true to some sort of high-falutin' "vision." We're talking fiction here, not sermons.
And I will argue to my dying day that TOS was never "utopian." Optimistic, yes, but full of drama and tragedy and conflict as well . . .