There's also a lot of contradiction. They won't want to be constrained forever if they are going to continue to do material in the mid-23rd century.
Don't forget the Guardian of Forever, there's a timeline out there where Spock was killed in his youth and Amanda Grayson died in a shuttle accident after divorcing Sarek. Spock's sehlat also died much earlier than it originally had. I've honestly never seen the big deal about the multiverse...