As a film producer yourself I assume that statement was tongue in cheek. If not, I suspect that at least a few of the following may choose to disagree with you:
John Ford, Kubrick, Lean, Welles, Fellini, Leone, Luc-Godard...
It was in part tongue in cheek, you did pick up on that. I couldnt resist a chance to poke fun at the 70s new Hollywood cinema, and the likes of George Lucas, Martin Scorsese, and Francis Coppola, yet the point of the argument is not so rightly cast aside.
The 70s are not my favorite time for movies. But I will also say it is a fool's argument to propose that any older film is superior in terms of production quality than a modern film, and the art of storytelling and even acting, though I often consider that to be a very secondary piece for a film, has improved over the years.
Classic films are classic for a reason. They broke ground, the established new methods. But some of the great works done in the past 25 or so years is quite impressive, and holds up very well when compared to the old Film Noir classics, or even dare I say Citizen Kane.
With that all being said, citing Kubrick wont go far with me. I have little to no respect for that man's style. Orson Welles on the other hand. A masterful story teller. His filmmaking was very ahead of his time, and is how he should be remembered really for all his work, that he was ahead of his time.
But to cut short that anything made after WWII as being not worth the time to see....nope I cannot agree with that at all. The top of my list of the greatest feature productions of all time consist of a number of films that were made in the past 20 years or so.