I'm saying a guy like Darrem can do more with those 40 lb. dumbbells in terms of stimulating biceps growth, than less skilled and focused trainers could do with, say, 65 lb. dumbbells.
Exactly.
Look at the form his using
look at the concetration on his face.
He's back is 100 percent straight, elbows tucked into his sides on the curls, elbows locked on the extensions, going by the look of the pics, he is trained superslowly too.
Maybe you guys should start training this way too, and you might look a bit more asthetical.
Bodybuilding is about "stimulating" your muscles.