She just barely provides it in most situations. Unless the person is already incredibly close to cover, she barely extends the time for someone to get to cover and peel for healing anymore.
And once peeled, the only people who get out back into the fight fast enough are the squishies and even then it feels slow considering.
If you peel, which means you literally stop taking damage to get healed to full which shouldn’t take that long because you stopped taking damage. It shouldn’t ruin the pacing of your fight to peel for a support who is supposed to act in a main support position. It does for Mercy. If you have to stand there, tapping your toes and have time to alt tab and send a small message, etc. while Mercy is healing you OOC, then that is a problem. (Which I have done as D.va. I stood behind cover and waited for my healing and had time to send off a discord message and come back because healing from Mercy takes that long).
You don’t have to spend forever peeled for Moira or Ana. You do for Mercy. That is a problem.
Mercy having the ability to heal someone out of combat situations or after they haven’t taken damage for ___ amount of time would merely allow her to get someone back to the fight at the same pace as other supports that she contends for a position with but does not give her the capacity to keep them in the fight longer or drag out the length of time which someone could peel.
Peeling should merely be a small moment where you avoid taking damage to return to the fight with fresh health.
That peel should not take too long as you already sacrificed some ground backing off to get healed to try and push back later.
If it takes too long, then people will not want to peel because then they keep losing the ground they are holding to peel for healing.
That is the problem with Mercy and her current healing rate with peeling potential.