and...you just said it again
I did watch the NBA in the 70's, 80's, and 90's. The court hasn't changed, the shot clock hasn't changed. The 70's and 80's had higher pace than the last 10 years. The average pace 10 years ago was 93.9. 10 years before that it was 90.8. Ten years before that it was 92.7.
the Showtime Lakers would have crushed the Pacers. So would have Bird's Celtics. Jordan's Bulls would have done the same. And the bad boys Pistons. Trying to defend those teams was the epitome of "physically demanding". As far as intensity, Bird, Magic, Jordan, Malone, Stockton, Pippen, Laimbeer, Moncrief, Malone, Barkley, Lever, David Robinson, Hakeem....those guys were every bit as intense as anybody playing today, and they weren't alone