Unfair Comparison: 1940's Dairy (Organic) Versus Now?

From Farm Policy, quoting a release supporting production agriculture as environmentally friendly:

The update also pointed out that, “Dr. Jude Capper of Cornell University reported last year that more milk from higher-yielding cows that are fed more grain and less grass have helped reduce the carbon footprint of the U.S. dairy industry by 43% since 1944.
“‘Interestingly, many of the characteristics of 1940s dairy production — including low milk yields, pasture-based management and no antibiotics, inorganic fertilizers or chemical pesticides — are similar to those of modern organic dairy systems,’ Capper noted.”

I'm not sure that's a particularly fair comparison.  I'm reacting because I was brought up on a 1940's dairy farm.  We did use penicillin for mastitis, however. If I remember our production was about 11,000 pounds per cow, which was quite a bit above average.  Today I think the average cow is much above that (more like 20,000 pounds).  I suspect most of that increase is breeding, not feeding. If that's true, the comparison doesn't work, because there's nothing to prevent organic dairies from having the best-bred cows.