From the article: "There are many things in life you are or can be responsible for, but the date of your birth is not one of them. When I meet someone who makes too much of their calendar age..."

Doesn't sound to me like I'm missing his point.

40 year olds have different strengths and weaknesses from 20 year olds. Very few people, possibly zero, can transcend that. I can't. And it's stupid not to adjust your game to suit your strengths.