Heat dissipation is a factor of amperage (solely) in the wire, and higher voltage means lower amperage for a given amount of power. Literally.
[https://en.m.wikipedia.org/wiki/Ohm%27s_law]
The challenge here is that above a certain voltage, insulation gets prohibitively difficult (and bulky), which makes solid state electronics to control and manage it also prohibitively difficult. And leakage current becomes dangerous.
For example, we could run chargers at 1 million+ volts, and use standard 12 awg stranded cables to do it with very low losses (and low heat) at megawatt charging rates.
But the insulation would be crazy thick (inches?) and if there was any damage or minor leakage, it would be very dramatic very quickly. Like ‘mini nuke’ type arc flashes. And because the distance you can strike an arc in air with 1 million+ volts is measured in multiple feet.
P.S. NACS is just CCS with a different connector.