> I cannot think how starting from already hot water vs. letting the water warm up and boil from the stove, could make any noticeable difference.

The idea is just that the beans don't get cooked as much by the heat ahead of the brew phase. For me it's made a big difference.

I also think there might be more of a heat gradient in the moka itself, i.e. the upper compartment including the vertical tube might end up with a lower temperature throughout the process.