One problem may be that you are not taking time evolution into account. Steve Jobs not being born and Steve Jobs being born are similar at conception. But because life is great at turning small changes into bigger changes, once the ovum starts replicating they can be quite far apart, and of course many years later there are huge differences :)
It's like chaos theory and predicting the weather - states might start out close together, but even tiny differences can give you totally different futures, because the difference can grow exponentially.
Nearby Everett branches will indeed look like one another. Right now, we're pretty far away from "no steve jobs" universe. But we were close in the past, which gives it that nice "alternate universe" feel.
And yeah, welcome to the wild world of infinite-dimensional spaces.
I started to form a counterargument and then realized that I had a really different (and unjustified) model of what was going on. Suppose one quantum state is different in one branch compared to another. This one state being different creates a ripple effect of new interactions that happen in that branch that can not happen in the second branch. Thus over time, the branches increasingly diverge in the similarity of their quantum states.
This updates my view, which was imagining a particular Everett branch as a 4 dimensional "matrix" of random numb...
From Quora: