The Keeper wrote:
Agreed ^ and a major change the reboot accomplished is changing the way Time Travel works in Star Trek.
It has rebooted the single timeline staple of Trek TT with many worlds theory which means any attempt to TT will result in the traveler switching timelines just as Nero, his crew and Spock did. Any attempt to "go back and repair" something in a travelers timeline of origin will only screw up (alter) things in a new, innocent timeline.
For the purpose of this topic we have to understand, (and accept) a fundamental change in the way "Spock" thinks after coming through the blackhole. He longer thinks of TT in the same way many fans still do; the single timeline. "Going Back and changing the past" is no longer how he understands Trek TT science. His way of thinking has been converted (rebooted) to align with Many Worlds Theory and therefore he now knows any attempt to TT will not achieve the desired goals in the timeline he now occupies. His best option, to avoid screwing with other timelines, is to make the best of his current situation.
I believe this to be one of the Paradigm Shifts they intended to achieve in Star Trek. All the above is, of course, my opinion.
Orci and Kurtzman pretty much said the same thing years ago. This is a new way of looking at time travel for Trek. It's also more theoretically acceptable these days than most of the other ways Trek looked at time travel.
In this way of thinking, if Spock "went back in time" to save Vulcan from being destroyed, he may well succeed, but restores nothing in the timeline he came from. Instead, he just creates a new timeline where he lives with an intact Vulcan. Vulcan in the timeline he came from is still destroyed.
It's the same reasoning for how Spock Prime "going back" in time in ST09 changed nothing about the future from that point on in his old timeline.
At Delta Vega, Kirk simply wasn't technically correct when he challenged Spock Prime about going back in time and "changing history" and "cheating." Spock Prime even more or less joked about that to Spock at the end of the movie when he said he let Kirk infer certain "universe ending paradoxes" would occur if Kirk divulged that Spock Prime existed. They won't. Spock Prime belongs in that universe just as much as Spock does.
There is no "in-universe" reset button.