It's also partly a 'Europe versus USA' thing! The VU 'standard' was cobbled together by Bell Labs, CBS and NBC back in the late 30's or early 40's. They optimized it for radio broadcasting primarily, but for all sound recording in general. I don't think those Bell labs scientists would have liked the way you describe their pioneering efforts, by the way those labs were an international bunch of scientists cobbling stuff together as the first in the world at that time. PPM just like PAL came later and was in part build on the lessons learned from Bell..