I'm inclined to think that like most things even fads like YO YOs and recessions come in twenty year cycles,
The first scrambles meeting I saw was at Moorebank '50 or '51, My cousin took me there on the back of his new Matcho. twin.
I was about 12yrs old. The spectator crowd was massive. The only riders I remember were the Jarvis brothers standing up but sitting down on there' outfit.
This wave continued through the 'fifties into the '60s with even a major event being direct televised. It got a boost through the early '60s by virtue of being the only licenced track in NSW along with 'The Showground' meaning nowhere else to ride.
Then it slowed a bit waiting for the next wave.
cheers pancho.