You are wrong. Physics doesn't change with newer technology.
As the article makes clear, getting the same coverage pattern at different frequencies requires antenna modification and a change in power. You're assuming that you can use the same amplifier and depending on how far the move in frequency is, that may not be possible. Anyone moving from UHF to VHF will likely need a completely different transmitter, antenna(s) and a new elevation; perhaps on a different tower. None of these is a matter of flicking a switch.
Just as it is with your 91XG that is UHF-only, stations going to VHF (whether high or low) will have to do something entirely different to work with the VHF band where the wavelengths are much longer. The wavelength of RF13 is about 55.77" while the wavelength of RF14 is about 25.12" (less than half). The wavelength of RF2 is upwards of 17'.