FFXI is a good example of healers never needing to DPS really. For one, healer DPS was nearly non-existent on any relevant content due to extraordinary accuracy/evasion/defense checks, which mages didn't come anywhere near close enough, and also extremely low potencies on any and all damage spells. That said, battles were not scripted, so healers had to always be on their toes to heal and remove debuffs (which almost everything was raid wide debuffs). Healers had to upkeep single target buffs on themselves (refresh,stoneskin) as well as making sure tanks were always capped because damage was unavoidable/undodgeable, and tank cooldowns were 3-5min each.