we had a proper dot mage, it was called scholar. A niche that suits a healer so they can do plenty of damage while theorectically healing (I say theorectically because of SE's aversion to making incoming damage significant enough to require more than a single assize or medica 2)

reaching the debuff limit was what caused them to lower the amount of debuffs available, yet now we got 48 player raids with their debuffs and apparently that doesn't hit the limit? Bring back sch dot mage!