Mirror universe headcanon

So, we've seen a few times that there are multiple parallel universes where things are different in a way that is important to the characters, like they're a ruthless sexy intendant or they lost at a bat'leth tournament.

I don't think it's ever stated that there are infinite alternate universes (there are at least 285,000), but you would think that some butterfly effects would happen in some of them. Some amino acids don't combine, so humans don't exist. How come we never visit those universes?

It is my headcanon that the physical differences between universes create a sort of "distance" between the universes. Universes very different from the prime universe, where physics work different, or entire races don't exist, are very difficult to reach.

Universes very similar can be accessed. While Humans subjugating Vulcans instead of cooperating with them is a big change geopolitically, that's not really something that differs much in physical sense; it still involves Humans and Vulcans on spaceships. Kind of like how Dr. Manhattan sees an alive body and a dead body to be nearly identical as they're comprised of the same particles, this universe "distance" doesn't care about who is allied with who and who is dead or alive.

This leaves the problem of the Mirror Universe. Physically, very similar because all the same people and ships and planets, but surely not the most similar. We've seen a universe where one of the only changes is Data's eyes are blue. Why is this not the most easily accessed universe?

The second part of my headcanon is that the universes flow like a river. They can diverge only to recombine later. The two universes that diverged on what painting was in Worf's room recombine later when the Enterprise-D (and the paintings) are destroyed.

So the Mirror Universe is simply that closest universe to the prime universe that has yet to recombine.

Feel free to poke holes in my theory.