So what? What anything has do with the fact that they were or were not strong as modern bodybuilders? In bodybuilding it isn't about the strength, it is all about how lifting make your muscles grow, and to do that you don't need enormous weights. Those oldtimers know much more about stimulating muscles, while these modern bodybuilders know more about shortcuts and chemicals. So what? So that's why those oldtimers had far more aesthetic appearance, while these modern day mass monster are like sack of random bodyparts put together. Legs from the horse, middle section from the pregnant lady etc.. 
I mentioned "heavy" because the guy I responed talked about building a foundation with heavy lifting. The term heavy means so many different things to different people that it's almost meaningless without lots of qualifications. Heavy means lifting so heavy you have to cheat to one guy, to another it simply means low reps and then there are those pros who say "I lift heavy as shit but do tons of reps too" LMAO, that makes no sense whatsoever. But let's say "heavy" simply means hard training in general and that you are putting intensity and effort to the thing. Yes, having a good foundation and good work ethic is important, chemicals or no chemical. However, it's silly the way some oldtimers cry about lack of foundation and no intensity in the new crop of guys. Meanwhile they started juicing at 14-15 years old and then at their peak were squatting maybe 315 for 20 and todays supposed lazy ass kids are banging out sets of 20 with 500lbs still in their teens.
Today's children wannabees are food prepping and counting macros, studying the drugs... I mean that should signal that they are serious, but the response from the oldtimers is to scoff at these new antics. Then they start talking about how kids nowadays are taking things too serious. Back in the day Rich Gaspari was thought a maniac for weighing his spaghetti - nowadays that's something you simply do, nothing to brag about.
So you see how the conversation becomes ridiculous when different generations clash.
The older generation does NOT know more about "stimulating the muscle". They believed a ton of ridiculous things. Like high incline benches would give you split pec line like Franco, or doing concentration curls like Arnold would give you his bicep peaks, absolutely moronic stuff.
Along with the idea of sculpting your body like an artist in the gym, when even someone with half a brain understands body shape/muscle belly shape/separations between muscle, detail and striation, and basic prportions and symmetry has almost nothing to do with training. And no, a 10lbs dumbell will not grow your bicep as much as a 40lbs dumbell, everything else being equal. But you had these oldtimers bragging about their mind-muscle connection, and how they could grow just as well squatting a broomstick because of their superior mind-muscle connection made them so efficient lmao.
