On one hand you say that FP aficionados are unable to explain FP concepts to others, and on the other you succinctly do it later on in the same paragraph (first

On one hand you say that FP aficionados are unable to explain FP concepts to others, and on the other you succinctly do it later on in the same paragraph (first class functions, closures, partial application). I think you're conflating Haskell with FP, which is definitely not the case. No one needs to understand category theory to write Clojure or Lisp.