Right - I took the comment to be about working sane hours yields better results than working twice as long... and generally older folks are less inclined to work the 2x hours.
Even though you personally haven't observed any correlation, wouldn't you think that experienced people can make better judgement calls when designing software? Because of their experience (age), that is. Personally I feel like I'm 10x the developer I was 20 years ago. And that is 100% because of the experience and years. One learns while doing you know.
I've worked with very smart, cutting-edge literal graybeards who could code circles around me, and guys who have been at the same company in the same entry-level or mid-level programming job for 25 years yelling in a meeting about "this damn web shit."