That would be their identity if they weren't crippled by ACC requirements (while the other healer jobs have abilities that ignore ACC) or crippled by MP management (again, the other healer jobs have abilities that mitigate this deficiency). If SE wants to keep these as-is, DPS will never suffice as a WHM identity.
As the job stands right now as of 3.4, WHM has the largest number of drawbacks and limitations of every FFXIV job.