Except.... there's no particular technical reason that each of the modulation techniques can't be good if you have the right filters for the desired bandwidth. I can adjust my Ten-Tec Orion II to transmit 3900 Hz bandwidth SSB - and it sounds glorious. Also, I find it interesting that aircraft still use AM. BSG? They tended to be fracked audio-wise by being slightly off-frequency in addition to various amounts of AM distortion that varied with the situation's distress. So say we all.