Yes, the high potency with added stun looks OP but they offset it by making the cast time longer than the gcd + extremely high mp costs thus making it a low DPM(damage/mp) which is very inefficient dps esp to whm whose mp is one of the most precious resources compared to a sch's mp(always make comparison to other classes on the same role). Decent whms found niche encounters to unleash the true potential of holy to devastating effects bypassing the mp management needed for holy thru ooc mp regen & ballad and no aoe limit is just icing on the cake with each additional monsters being calculated as extra dps which just make holy dps skyrocket during a 10 mob pull.