The old cam was really designed to work in a 10:1
440/3400-3600lb car environment.

By the late 70s/early 80s, 8:1 engines with 40 less CI and 4300lb cars were much more common. People were installing the hemi grind into 1973 400s in a 4300lb car, and were then complaining about the cam characteristics. Not enough low end pulling power, poor idle and so on.

Around the same time, the 272/.455 was also developed in order to be a nicer B engine cam, where there is no compression, gear or converter to fall back on.

The 272/.455 is the sleeper of the mp cam lineup.