Even though she currently has the highest pick rate
She has the highest win rate of any support
She has the strongest solo healing output
She can bring a teammate back from the dead every 30 seconds
Her ult allows her to fly and make her almost unkillable
She can instantly hover to any teammate at almost any clear range every 2 seconds
Now give me a legitimate reason Mercy needs a buff
Oh and not to mention she passively regenerates health