Not to defer your point, but Dane Cook is only around five or six years younger than Louis, and Dane was doing comedy/stand up since he was at least 20 according to his wikipedia. Dane Cook hasn't been young since his career skyrocketed in the 2000's and cratered not long after.
Louis CK sorta rose up around the same time as Dane even. Louis worked with a lot more prestigious comedians than Dane did in the 90's and early 2000's, eventually his specials got enough attention that he got his own show on HBO.
I'd say the older a comedian gets, the better they get at reading a crowd or just performing in general. But the material and delivery itself is all derived from personal skill, craft, and natural comedic talent.
Dave Chappelle, Bill Hicks, Hannibal Buress, Eddie Murphy, these comedians were all at the top of their game in their late 20's/just turning 30.