If i wanted healers to be buffed, Id just lower the damage enemies do or raise health pools more.
Then nerf healers by going after their cast speed/HOT tick rates/mana consumption (Sounds dumb I know)
The more healing output we do the more damage they make monsters do and we end up seeing constant 100% - 10% spikes.
If they increased health pools and lowered damage, then also lowered our healing you would see less wack-a-mole healing and more tirage healing.
See a dps at 40% HP but you know they aren’t taking damage, you can focus on someone else who needs it more.