I do know this: MND is associated with Water, which is tied to Poison, among other spells.
Poison is INT-based.

At the idea that DRK can't perform many of its, logically, self mutilating abilities and survive without the assistance of other jobs, I point out that the developers try, in many different ways, to encourage and require players to participate in group activity.
Absolutely.

So why would someone participating in a group activity given a choice between DRK and OtherDD choose DRK given DRK is going to require a lot more mage attention and stand a higher chance of dying if it uses its self-mutilation abilities which are necessary for it to still be below the damage of OtherDD?