No, Physiques like Zane's and serge's just look about a 1000 times better than modern bodybuilders. It's not partcularly complex.
No, it's not particularly complex. Bodybuilders that preceded Zane and Nubret said the EXACT SAME THING, that their bodybuilders looked better than "modern bodybuilders".
The point, which you seem to have missed, is that EVERY ERA claims that their bodybuilders were the best and that the succeeding/current era of bodybuilders..."aren't as good", "all look the same", "are bloated steroid freaks", "don't have the comraderie that we had", etc.
The guys from the '50s said that about the guys of the 60s; the competitors from the 60s said much the same about the 70s and 80s bodybuilders. They, in turn, hurled the same comments at folks from the 90s/early 2000s. And now, those folks are talking that same stuff about the current competitors.