From a BMI perspective, this gauges only height-to-bodyweight ratio. Most of us that lift weights will fall into the "overweight" region. However, if you extend into the "obese" range - unless you're an NFL running back or juicing, you're also fat. You may be strong and fat, but you're still fat. I've come across so many dudes that say "I'm 6' and 240, athletic build....". No, lose 50 lbs and you'd have an athletic build, but as it stands now you're simply an obese dude that is strong.
I've seen dudes in their 20's that were "obese but strong", and they excelled at sports, could put up huge numbers in the weight room, and felt great. But 15 years later? They had bad knees, bad backs, and were in sad shape. They still ate with the best of them, though.
So, again, who cares if a 600 lb DL is "possible for everyone" if it requires obesity and all that comes with it? There are certainly studs that can pull this weight as impressive, healthy physical specimens; but no, I don't think "everyone" or very many at all an achieve this.