supports legit have minimal ways around helping an anti’ed ally live. the only real thing a support can do to help an anti’d ally is to lucio beat.
and that’s the problem here: a main healer with an ability to hard counter her competition —> inherently higher on the support balance hierarchy.
to overcome such a hard countering ability with buffs to the other supports, they’ll need to be at least overturned.
mccree flash bang isn’t a problem at all due to its inherent short duration and how its range limitations allow for more global counterability.