Not junk science at all. Stray voltage is real and it can cause problems.
I was on a 4 week jury trial several years ago where a local farmer was suing the power utility for the damage stray voltage was doing to his milk production.
It's as simple as this: All electricity generated and sent out the wire must come back to the generation point. How much of that returns via the neutral vs through the earth depends primarily on the condition of the neutral. Electricity ALWAYS follows the path of least resistance. In the testimony I heard, the utility itself indicated that something like 12% returned on the neutral, which meant that 88% returned through the earth. It;s been a long time and those numbers are probably not exact, but I was shocked (no pun intended) how much current was going through the earth. If the conditions are right, the path could indeed be down the metal of a water line which could indeed cause you issues if you became part of that circuit.
It's simple really.
Good post, but to clarify this statement. Electrical current flow will follow ALL paths, it will be in reverse proportion to the resistance.