I disagree with your conclusion. Specifically, I disagree that
This is, literally, infinitely more parsimonious than the many worlds theory
You're reasoning isn't tight enough to have confidence answering questions like these. Specifically,
In order to actually say anything like the second that's consistent with observations, I expect your physical laws become much less simple (re: Bell's theorem implying non-locality, maybe, see Scott Aaronson's blog.)
A basic error you're making is equating simplicity of physical laws with small ontology. For instance, Google just told me there's ~10^80 atoms in the observable universe (+- a few orders of magnitude), but this is no blow against the atomic theory of matter. You can formalize this interplay via "minimum message length" for a finite, fully described system; check Wikipedia for details.
Even though MWI implies a large ontology, it's just a certain naive interpretation of our current local description of quantum mechanics. It's hard to see how there could be a global description that is simpler, though I'd be interested to see one. (Here local/global mean "dependent on things nearby" vs "dependent on things far away", which of course is assuming that ontology.)
With all kindness, the strength of your conclusion is far out of scope with the argument you've made. The linked paper looks like nonsense to me. I would recommend studying some basic textbook math and physics if you're truly interested in this subject, although be prepared for a long and humbling journey.
I recently stumbled upon the concept of "reflexive self-processing", which is Chris Langan's "Reality Theory".
I am not a physicist, so if I'm wrong or someone can better explain this, or if someone wants to break out the math here, that would be great.
The idea of reflexive self-processing is that in the double slit experiment for example, which path the photon takes is calculated by taking into account the entire state of the universe when it solves the wave function.
1. isn't this already implied by the math of how we know the wave function works? are there any alternate theories that are even consistent with the evidence?
2. don't we already know that the entire state of the universe is used to calculate the behavior of particles? for example, doesn't every body produce a gravitational field which acts, with some magntitude of force, at any distance, such that in order to calculate the trajectory of a particle to the nth decimal place, you would need to know about every other body in the universe?
This is, literally, infinitely more parsimonious than the many worlds theory, which posits that an infinite number of entire universes of complexity are created at the juncture of every little physical event where multiple paths are possible. Supporting MWI because of it's simplicity was always a really horrible argument for this reason, and it seems like we do have a sensible, consistent theory in this reflexive self-processing idea, which is infinitely simpler, and therefore should be infinitely preferred by a rationalist to MWI.