Natural bodybuilders do not maximize muscle mass increase due to the demands of their competition. Nor do weight-class athletes in other sports. That makes these populations a poor example to demonstrate your point.
Steven, I agree that a lot of people on the internet do not eat enough to gain the strength and muscle mass they could attain with a higher calorie diet. That is going to hold true across averages, the problem is how much MORE calories, and not knowing when enough is enough.
The quote about natural bodybuilders is not really the case though, especially if you look at what they really do, and why they do it. The reason they dont gain a massive amount of fat in the offseason, to further push size is not due to them not wanting to get larger, its that they cannot make those same drastic cuts that the chemically enhanced guys do, without losing a lot of muscle along the way.
The guys marty refers to in the interview are highly likely chemically enhanced. Ed coan, kirk, etc. , are all very vocal on their "supplements", and making a drastic cut with the assistance of drugs is much more doable without losing all the muscle tissue you gained during the hardcore bulk.
This topic has been beaten to death on tnation with the competitive natural bodybuilders. Guys that are "big" telling them they should eat more calories, then they tell said "guy" to cut down to competition weight without drugs and see how big he really is, or stays. Its the same reason the general rule of not "bulking" until 12% or so, I think that is lyles general rule of thumb, and it fits with what has worked for naturals over time.