Their rarity is clearly true. As for the grandiose assertion of superiority, it's worth noting the context: Lisp programmers never develop the social skills nee

Their rarity is clearly true. As for the grandiose assertion of superiority, it's worth noting the context: Lisp programmers never develop the social skills needed to work effectively as a member of a team. Fred Brooks didn't see Lisp as a silver bullet, which a "vastly more productive" language would be. I'm sure he talks about functional languages specifically in his retrospective essay "Still no silver bullet" (or something like that).