I really don't get why people always advocate for PLD to have more mitigation tool. PLD already have its 3rd mitigation button in form of Intervention. Plus it have the biggest % mitigation in the game, Holy Shelltron being a 20% + 15% with Intervention being 20%+10%, they are both the 1st and 2nd biggest % mitigation button compared to all tanks. While Holy Shelltron 20% doesn't block DoT but you have to consider that giving Intervention to your co-tank makes them take almost 0 damage from DoT. This creates a situation where your co-tank needs 0 healing and so your healer can focus more of their resource on the PLD instead which fits in the job fantasy of PLD being the "protector" tank.

To prove my point if you check Damage Taken stats, a tank comp with PLD in it that actively uses Intervention on each tankbuster they would actually be taking less damage compared to any other tank comp that doesn't have PLD in it. The damage gets even lower if the co-tank gives PLD their personal mit