The above write-up exhibits a lack of understanding about how quantum mechanics works, to the point where it dismisses the Many-Worlds Interpretation (MWI) of quantum mechanics (which is considered to be true by most physicists who study this sort of thing) with two paragraphs of conjecture and pseudoscience. The fact is that while Copenhagen is the prevailing theory in popular science, the majority of people doing work in the field of quantum mechanics ascribe to MWI, because at the base level they both make sense, but as one dives deeper into theory, more and more problems arise with Copenhagen while the number of problems with MWI remains generally consistent. Now onto why the position taken above is incorrect.
Consider the list of real numbers between 0 and 1. It should be intuitively obvious that this list is infinite. It should also be intuitively obvious that the number 2 is not in the list. Neither is 3. Or 4. This simple example shows that not only does an infinite list not contain everything, but that the list of things that are excluded from the infinite list can itself be infinite. The list is bound by certain parameters - only numbers between 0 and 1.
Just as there is an infinite list of numbers that aren't between 0 and 1, there are an infinite number of universes that cannot exist in MWI. Where waveform collapse would occur in other interpretations, universes decohere in MWI to account for all possible outcomes of the would-be waveform collapse. But, and here's the important point, all of these universes are bound by the same parameters. If the gravitational constant of the universe is 6.7428 x 10-11 N (m/kg)2 before the split, all of the worlds created after the split have the same gravitational constant. Impossible things, by definition, cannot occur. So while there may be universes where you are dead, or dating Scarlett Johansson, or working as a regional collections supervisor for a box company, there are no universes where electrons weigh more than protons, or where the weak force doesn't exist, or where causality can be violated. If it can't happen here, it can't happen there.
This leads to another factor that isn't considered above. The definition of MWI itself precludes communication between universes. This may sound convenient - after all, if no communication can occur between worlds, how can anyone ever prove or disprove the theory? The answer is beyond the scope of this writeup, but suffice it to say that universes do not interact with each other, but they do interfere, and given sufficient technology (which does not exist yet) this can be detected. The point is that MWI prohibits travel between universes. That means that if it's not possible here, it's not possible anywhere, and if it is possible here, MWI is wrong. The two are mutually exclusive.
Now, to clear up a few misconceptions in the above writeup:
"Consider that the typical electron makes several million such jumps every second, and multiply that by the number of electrons in this galaxy alone, and you're immediately speaking of an uncountable number of spinoffs -- as in trillions to the trillionth power -- in the first few seconds out of the gate."
MWI splits only happen when a thermodynamically irreversible event occurs. While events like these are common occurrences, the orbit of an electron around a nucleus does not constitute such an event.
"First, you could justly argue that all of these alternate Universes exist, but there is no way for events in one to affect another. This proposes a limitation on the power of science to act, and more importantly suggests that it is impossible for us to ever know if indeed there are any alternate Universes out there, because as the Heisenberg uncertainty principle relates, there is no way to observe something without altering it in some way."
First, there is always a limitation on the power of science to act. A very basic example: it's impossible to accelerate anything with mass to the speed of light. Period. End of story. There may be a way around this fact (for example, an Alcubierre Drive), but no science is going to override this. Second, the Heisenberg Uncertainty Principle does not state that there is no way to observe something without altering it in some way. This is Syfy Channel science. All Heisenberg says is that there are pairs of physical properties for microscopic objects that cannot be mutually determined to some arbitrary precision. The observer effect is what causes observation to alter that which is being observed, and it doesn't apply to macroscopic objects. Watching a dog run down the street doesn't alter the dog in any way, because it's not a quantum object.