Unfortunately this is simply not true, as Kamali, Kovacs or any guy with fried receptors and a big waist will tell you. If your obliques are much bigger 5 years down the line from heavy squatting/deads or whatever, then training the same way will not yield the same results vis a vis overall body shape.
Ronnie has famously trained the same way since the beginning, just altering his diet as Teh Chad or whoever sees fit. He has gotten stronger on squats etc, and his quads got bigger between 98 and 2003, but so did his waist.
I know drugs play a part, but basically it's hard to unbuild that muscle whilst still keeping quad size, Gustavo is a case in point now too. He's cut down on leg work to get his waist down again, now he has small legs and his waist is still big. Or Rich Gaspari. Jay had a smaller waist once. All these guys get big waists and don't know how to get rid of them, so if anything, they are forced to change their training in an attemp to combat this. Your body won't respond to weights the same after 30 years that it did when you first start training, its job is to adapt, and for many that's what it does, in a bad way.