That's bullshyt. How many players during that era scored over 30ppg in multiple seasons and still shot over 50% from the field.
I just told you entire teams shot 50% from the field. The pace was higher there were more FTA, transition defense was worse, you couldn't play zone defense.
In the '80's there were more volume scorers shooting 50% from the field than any other era. Bernard King, Michael Jordan, Larry Bird, Adrian Dantley, Kiki Vandewhege, Clyde Drexler, Mark Aguirre, Dale Ellis, etc. all achieved high volume scoring seasons with 50% efficiency.