The author doesn't dispute this at all. He's a chess grandmaster who is not mystifying chess, but pointing out how a lifetime of rigorous chess playing has taught him the value of concentration. He acknowledges that the very same thing occurs in people in other disciplines, athletes for example.
It's not an article about the virtue of nerds but about the combination of attention, flow experience and concentration, in the face of a culture that neglects all three but the latter in particular.
And I think he is very right and chess can teach us important lessons here, as can programming, or craftsmanship, or participation in the arts among other things.
Particularly important is the point about autonomy. Making concentration and understanding of our own mind through games like chess a priority is liberating. Through things like chess it is possible to move from being distracted by external rewards towards understanding one's own cognition the focus of life, without which no genuine thinking is possible.