Because he's a very gifted writer and an insightful social critic whose modes of reasoning and analysis happen to align closely with those most familiar and nat

Because he's a very gifted writer and an insightful social critic whose modes of reasoning and analysis happen to align closely with those most familiar and natural to the average HN reader. (i.e. he does humanities, but for people who use phrases like 'Nash Equilibrium' and 'prior distribution' in the pub)