the "branching mechanism" is not part of the fundamental mechanism of the everett interpretation. The "branching" is an emergent phenomenon similar to what happens when you mix to liquids of two different colors. At "some point" the the fluids intermix in such a way that you no longer distinguish them and finding the right boundary when that exactly happen may seem a bit "fuzzy", but the physics of what's going on is perfectly clear to anybody; the two substances are still there, but just mixed up in way that is completely intractable to reverse in practice.
Postulating that nature just does the Born rule is postulating an additional thing that nature does.
Postulating that hey perhaps we ain't that special and perhaps we should just think through the consequences of our own brains being embedded in the very nature we're trying to describe.
On one hand, it feels like we're adding a lot by buying into the Everrettian model, because it does require us to think and throw away some intuition about ourselves. But OTOH, it actually requires adding much much less to what nature actually does.
sure, it's not possible to distinguish it from some of the others.
This thread started with comparing it to some theories that instead invoked non-local effects, which would violate general relativity, so there's that.
All I'm saying in this thread is that, when comparing possible theories, the ones that do not violate general relativity while explaining other observations IMO deserve not to be dismissed just because people cannot wrap their heads around non-physical consequences of the theory.
That's literally what people claim Copenhagen to be
Everett's interpretation requires positing a universal wavefunction and some kind of branching mechanism
It's not some basic, straightforward interpretation of QM without any additional postulates, and even if it was, that would not be evidence for it to be true over others