Those were horse steroids back then. Anyone that took that stuff was out of their minds. I doubt that it was prevalent at all. Players in the 70s didn't even believe in weight training. They were told to avoid it and they did.
I don't put amphetamines in the same class as steroids. Heck, if they need something to keep them awake, let them have it. It's good to be alert when a 90+ mph fastball is coming at you. It didn't make them any stronger or faster.