OP got it totally wrong. Zen has tons of damage output and constant healing, Moira NEEDS to do damage in order to be able to heal efficiently. Plus the class is called 'Support', not 'Healer'. The class is there to make sure everyone else gets their job done much more easily. If it was specifically 'Healer' class, Discord Orb wouldn't exist, Moira wouldn't have such damage output, Lucio wouldn't have speed boost, etc.
Learn what the class is really there for please.
-Zen top 500 (America server).