self-expression

Self-expression must pass into communication for its fulfillment.
Pearl S. Buck

… and of course every speech or presentation is communication – hopefully even a conversation.
… but does self-expression need to turn into communication to be fulfilled? Can one express oneself just for the sake of creating something, for learning mastery? What about the value of a journal that no-one ever reads but that is so cathartic, and supportive of personal growth?
Am I missing something?