I'm sure that commissioner, like any reasonable person calling for a return to those traditions, is also calling for the abolition of the NFL, all volunteer coaches, and gratis, advertising-free broadcasts of all the games, right? Right?!
For varying degrees of "amateur". A lot of nations employed their athletes to do nothing but train for the olympic and international competition.
The Soviet Union and other government-controlled-economy nations were sending essentially professional athletes to the Olympics while free-economy nations were sending amateurs. Removing the restriction allowed all nations to send their best athletes.
Ironically of course, there are some aristocratic motivations for why "amateur" was desirable in the first place that don't really align to modern sensibilities, but that's separate.