Thanks for link Leo.
The article makes sense if you consider only resistive loads. But, as the article goes on to say, that's not the case with ac motors that are being discussed here. In these cases, higher voltage results in lower current (it's in the article). So, in such cases, the use of an autoformer to boost voltage reduces the current drawn from the campground.
OTOH in a low voltage condition, most folks would not run their air conditioner(s), fearing damage. If such a person decides to use an autoformer in that same situation and, because of their higher available voltage, runs their ac, then they will draw higher current from the campground than if they had not run the ac. This additional load (current) will indeed result in additional voltage drop along the campground line and the neighbor without an autorformer will experience even lower voltage. In this scenario, it's not the autoformer that's creating the additional load and lower voltage, it's the fact that the individual turned on their ac.
FWIW the guy in his article incorrectly calls it an autotransformer, which is a different animal (explained in prior posts in this topic). An autotransformer has a single winding with multiple taps, whereas an autoformer (at least the Hughes one) has separate primary and secondary windings (5 in all) which provide isolation between incoming and outgoing voltages. I should go research the other brand of autoformer.
FWIW I have an article in draft dispelling some of the myths I've read here and elsewhere. It's a long way from publication, but will be in our forum library when I'm done. No plagiarizing, all my own work. Hopefully I can back it up with some empirical data, although that might have to wait until I decide to buy an autoformer.