Oh you're playing on semantics. AST has lower healing throughput that the other two. Without them using their cd. That's all. If all three healers had only Cure or equivalent, Cure 2 or equivalent, Medica I/II or equivalent.. yeah the output would be the same. Except it's not how it works.

Edit : just to be clear, i don't want to be as strong as an healer as WHM. I just want our CDs to be buffed/fixed and some of our cards skills changed/buffed.