Did you think Arnold never took steroids?
Imo the Golden 'era' of bodybuilding is the 60's and 70's. Possibly starting in the 50's as X stated. Its when Arnold was winning all of his Olympia's and bodybuilding started to become popular.
Before then, men who lifted weights were considered 'gay' etc. Going to the gym was an odd thing to do.
After the Golden 'age' or 'era', whichever you prefer, going to the gym was accepted as normal, common, and cool.
Triple-10-sets I'm sorry but your incorrect.
To answer the OP original question, the Golden era was more a time when bodybuilding was first popularized and the gods or legends that we know of today (Arnold, Zane, Sergio, Nubret, etc) became noticed.
It was more a time where sculpting an aesthetic physique was more important than just flat out mass like Ronnie, Jay, and gang. I do believe, IMO, that bodybuilding is taking a turn for aesthetics again. MASS aesthetics, but definitely still aesthetics.
And yes, Steroids will still be involved...