Yoshi P said himself that SCH was overpowered(as well as WAR) and savage fights were basically designed around them, they weren't going to be touched until SB. Also WHM damage was only higher in strictly single target, if there was anything a SCH could Bane to it would win over.

Now for heals, if you conveniently forgot about Lily and and her healing steroid CD, Rouse + WD every minute and magic rampart CD, sure a SCH would run OOM quickly if he himself had to keep the group topped. Efficiency doesn't just come from mana costs and spamming your AoE heal though. A SCH who properly micro'd his fairy and his healing CDs rarely found himself OOM.