Im not an engineer. However, their simple demonstrations do seem to do the trick.
In my mind, the heavy part of the tire will essentially swing out farther than the rest of the tire, and all the beads will end up there sooner or later, which will make an imbalance worse. Hence, I call it witchcraft; not trying to steal their thunder or discredit what may be an outstanding product, the dots just don't line up in my simple mind.
As I have said before, I simply put the dot by the valvestem and have not had any shakes, vibes, wobbles, or negative side effects from it, and I don't balance my tires because they work without it. Modern bike tires are well engineered (battle axes being an exception in my opinion) and well built, right out of the wrapper.
30,000 mile 919 survivor. No plans of stopping the abuse any time soon.