I challenge anyone to prove to me that compound exercises are better than isolation ones. When you bench press or do pec-deck, the pecs adduct the humerus. They couldn't care less whether you bench or do any other exercise. "But", I hear you say, "with compounds I lift more weight, isn't that more beneficial ?" Guess what, you lift more exactly because they are compounds. For example when you bench you lift more because delts and tris are also lifting.
Anyway, this small introduction was just to say that after years of falling in the trap of "heavy compounds", I have managed to see some decent progress on my chest with pec-deck. Pec-deck is the only exercise that makes me feel the burn in my pecs while doing dropsets (even with flies, my wrists get tired before my pecs).
Of course the above is purely anecdotal, but so is the advocation of heavy compounds. There is no physiological reason to believe that bench is better than pec-deck. By this, I don't want to dump compounds, I just want to say that different people have different biomechanics. Several old-timers never used bench-press, while for others it was the king of exercises.