Because ZMQ is vastly better managed from a human POV. The energy required to make a project like this succeed surpasses the individual.
Really, I think it takes both a Hintjens and a Sústrik to make something great. (Or a Lennon and a McCartney, a Jobs and a Wosniack, a Rodgers and a Hart.) There's a tension between giving people something with integrity, and giving people something they'll love.