What was preventing older boxers from using PEDs?

Science and knowledge, basically early forms of steroids were more for gaining muscle mass and strength. Just like the perception that strength training (lifting weights etc.) is bad for boxers, then by logic so to would be steroids. But as steroids evolved, EPO, blood doping, different types of steroids that are for speed or strength without weight gain and side effects, so does knowledge of how the human body reacts to new training methods etc. Some old skool trainers, Freddie Roach for instance, still down play the strength training coaches as crucial to a boxers regimen but as we all know now to the modern boxer, strength and conditioning is just important as the boxing skill set. So in my opinion, its not that steroids werent there, and maybe some heavy's who werent worried as much about making weight did take them..... but the majority of steroids avaiable and the knowledge of those drugs were seen as counter productive to the goals of a boxer. With that being said, I think its pretty safe to assume a large majority of modern boxers are cranking, especially with the lack of reasonable testing out there.

I mean it's not like steroids are really something new, people have known about performance enhancers for years and many were legal in the old days. People used to take cocaine to cure a common cold. This pretty much goes for all athletes in any sport. What makes you think they didn't use them before ?