Your arguments make zero sense. Any tank skill that reduces damage taken reduces the amount of healing that needs to be done. Looking purely at the total amount of healing that needs to be done throughout a battle, the PLD skill that reduces it the most isn't Clemency. It's Shield Oath. Shield Oath on the MT is taking away 20% of the MT damage dealt during the fight, meaning there's 20% less total healing because of that one skill. That means it's intruding on the sacred realm of the healer and needs the damage reduction removed, right? Maybe we should remove all mitigation from tanks so the healer has more to do? Armor reduces the amount of healing needed too, and shields are terrible that way.

I guess PLDs should only wear cloth, only have swords, and only have access to DPS/aggro-generation skills? Well, the more DPS in a fight, the sooner it ends. The sooner it ends, the less total healing is needed throughout the fight. I guess we should remove DPS skills from tanks as well? It's not like they're a DPS class, after all. Let's remove all GLA/PLD skills except Savage Blade, Flash, and Provoke. That'll keep them pesky PLDs from interfering with a healer's job!