I can carry a heavy gun around all day if I wanted too. But if I can get a gun that is lighter, while still having the same performance, then I'll take the lighter firearm every time.
It's not about being a wuss, it's about being smart.
This guy sounds like a clown. Gotta love how he talks about how soldiers back in the day would carry around B.A.R's and Garands. Well, the loadout of a soldier is a lot heavier today than it was back in WWII. Sure, the guns were a bit heavier, but they also weren't carrying around the amount of equipment our guys today carry. Ounces turn to pounds, which can make a big difference when on foot patrol (so I've been told).
Now I'm not a soldier, never have been and probably will not ever be unless my country really needs me. But from people who I've talked to who have this experience, as well as reading other sites full of guys with a lot of combat experience (i.e. lightfighter), they will tell you a lot differently than what this guy says.
I agree with his point of getting stronger and fitter, that has benefits all around. But if you can save weight on your equipment, why not?