Yeah but do you think that's what the writers are looking for? They just created THIS timeline. They're looking to play with IT, NOT the gimmick of perpetual time travel. Trek, not Who.
And re Trek, the branching off universe is a new way of looking at time travel in Trek. Obviously in the past it was the same timeline they looked to alter, which again says something about why they wouldn't jump to use future Spock's knowledge right off the bat: there must be some Mutually Assured Destruction thing going on where no one does it for fear of everyone doing it. Either that or some timecops keeping things kosher.