Why is multi worlds not a good explanation for abiogenesis

Theistic proof from abiogenesis just passes the buck of improbability from abiogenesis to the existence of God that wills abiogenesis to happen. 

Invoking many worlds here will do more harm than good. Next thing we will have theistic proof from many worlds.

I'm not sure what you mean by objectivity or why superimposed states don't have it.

If a pair of superimposed state differ by a couple of atom positions, they can interact and merge. If they differ by "cat alive" to "cat dead" then there is practically no interaction. The world stays superimposed forever.  So that gives causal isolation and permanence.

I mean maybe some of the connotations of "worlds" aren't quite accurate. Its a reasonably good word to use. 

That's a good point! I was definitely unclear, and even sloppy in my claims.

My first statement, "makes no testable predictions" refers to "pure" quantum physics, specifically quantum mechanics and quantum field theory on a fixed spacetime background, where what the matter is doing does not affect, in the first approximation, what happens to the spacetime itself (which is the subject of general relativity). We know it is not a good assumption in general, because it leads to contradictions like the various black hole evaporation paradoxes. But it works within certain limits. Within those limits, many worlds add absolutely nothing new and predictable.

Sadly, the extrapolation of QM to the realm where gravity is still weak but already matters, is still an uncharted territory, over 90 years later. The generally accepted claim (but only a claim) is that the unitary evolution part of the QM scales up into the macroscopic world in some way, and the measurement postulate emerges from this upscaling eventually. Many worlds make a more specific claim, that we live in many worlds, decohering (splitting) all the time, and that there is nothing new happening beyond the basic decoherence. However, there is still the gravitational footprint of those worlds, unless you figure out how they split the spacetime itself, as well. In that sense, many worlds make a claim in the domain where QM has never been observed that is incompatible with the theory that rules that domain. it is still just an ontological claim though, without any predictive power in it.

Not sure if this makes sense.

Why do you call it complaining?

I stipulate that nearly anything can be a consequence of MWI, but not with equal probability.

Note that MWI postulates unitary evolution of the wave function, and in unitary evolution there are no probabilities, everything is completely deterministic, no exceptions. None. Let it sink in:

NO PROBABILITIES. PURE DETERMINISM OF THE WAVE FUNCTION EVOLUTION

There have been numerous attempts to saddle this unitary evolution with something extra that would give us the empirically observed probabilities. Everett suggested some in his PhD, many others did, with marginal success. The only statement nearly everyone is on board with is that, if we were to look for a way to assign probabilities, the Born rule is the only sensible one. In that sense, the Born rule is not an arbitrary one, but a unique way to map wave function to probability. The need to get probabilities from the unitary evolution of the wave function is not built into the MWI, but is grafted on it by the need to connect this theory with observations, exactly like the Born rule in the Copenhagen interpretation was.

That said, we might be on the cusp of something super mega extra interesting observed in the next few years, much more so than the recent black hole doughnut seen by the EHT: Measuring gravitational field from Schrodinger cat-like objects. There are no definite predictions on what we will see in this case, because QM and general relativity currently do not mix, and this is what makes it so exciting. I have mentioned it in a blog post discussing how MWI emerges from unitary evolution:

https://edgeofgravity.wordpress.com/2019/01/19/entanglement-many-worlds-and-general-relativity/

There is some discussion of this issue online, and I have mused about it on my blog some time ago:

https://edgeofgravity.wordpress.com/2019/02/25/schrodingers-cattraction/

Many worlds says that our socks are always black.

Nope. What distinguishes worlds, if their contents are the same?

The Copenhagen interpretation says that us observing the socks causes them to be black.

Nope. That would be consciousness-causes-collapse. Which is a different theory.

According to this theory, there is a fundamental physical difference between a complex collection of atoms, and an "observer" and somewhere in the development of life, creatures flipped from one to the other.

You seem to refer to some strawman version of the Copenhagen interpretation that no physicist subscribes to. Being brainwashed by Eliezer's writings can do that. He is very eloquent and persuasive. Consider reading other sources. Scott Aaronson's blog is a good start. Wikipedia has a bunch of useful links, too.

Start here reading articles by Page, Carroll, Smolin, Linde, Bostrom.