I didn't read about any magic. It's just science.
"This is analogous to the low frequency and high frequency signals being present in the same cable; they have combined within the transfer medium to create a new frequency which was not in the original signal in a process known as
intermodulation. Wherever there is non-linearity in a system which carries multiple different frequencies there will be amplitude modulation made up of the sum and difference of the original frequencies and in addition, harmonics of these sum and difference frequencies. Unlike some types of harmonic distortion this type of distortion is not nice to listen to and although non-linearity in good hi-fi equipment is generally very small, it is enough to produce intermodulation distortions which are bothersome to the listener."
They seem to be selling the notion that the intermodulation effects from all of those frequencies sharing the cable run can somehow be heard, to the point that we'll notice an improvement if we separate them.
Which is just a can of worms, because there are *still* intermodulation effects on both separate runs as well. The frequency range present on each cable is narrower, because the cross overs have partitioned highs from lows, but as long as there are a range of frequencies present, nonlinear to each other, there will be a sum and difference between these frequencies and will create another frequency. Albeit, smaller in magnitude.
What we really need is hex wiring. We need 16 runs, with 16 cross-overs splitting up the spectrum into 16 chunks - then we'll REALLY knock out the intermod.