Calling athletes "freaks of nature" does both a disservice to athletes in general and his argument in particular. He falls into the same trap of missing the fact that regardless of talent or genetics, if you don't work your tail off, you aren't ever going to amount to much. Just because you're born tall, doesn't mean you can play basketball any more than if you're born as Scott Adams, you can play pool. It still takes an inordinate amount of work to become a "professional" at anything regardless of your starting point.
I don't see how it's impractical to keep a log of how much time you spend practicing something. It can be as simple as placing an X on a calendar or as complex as keeping a detailed journal. Once a person does that, they can typically begin to track their personal progress in any particular skill.