People gorging on 6k cals a day are not gaining any extra muscle than someone eating 3k
They are just getting fatter.
Not necessarily. All of those guys bulked up in their formative years.
Franco, Arnold and Zane all gained weight going into a contest. Yes I know they are steroid guys. The bulk and then diet down system of the early 60's is nuts. Gain lean muscle.
Look at some of Schwarzenegger's early pics. Even Vince Gironda called him a "fat f--k". He was smooth but was winning contests. You may recall there was a time where bodybuilders got marked down (i.e. Gironda himself) for being too ripped, as it was deemed unhealthy.
If you're skinny, trying to gain just lean muscle is an exercise in futility. Going from a 160-lb twig to a 165-lb twig in a year is going to make you want to take up badminton.
These guys ate lots of beef and mixed their protein drinks with heavy cream. Larry Scott, the first Mr. Olympia, swore by it.
I grew up (bodybuilding-wise) in the late 80s and 90s, when John Parillo first started his (up to) 10,000-calorie-per-day diet. He predicted that bodybuilders would one day be competing at or over three bills. People thought he was nuts. But, soon we had 316-lb Lou Ferrigno at the 1993 Olympia. Gunter Schlierkamp (though not super-ripped) competed at 300. He actually placed better when he weighed less.
Steroids or no steroids, few (if any) get super-big without putting away the groceries. There are a handful of anomalies to this, just as there are those dudes who get ripped with no cardio (Dexter Jackson in younger days).
