DRK is definitively squishier in trash pulls. It's not really something that's debatable. You can say "but you have tools" all you want. Their tools aren't "press 1 button" - they consist of knowing and understanding the Job's mechanics and executing them properly. DRK's trash tanking really shines when you blind the enemies or boost dodge rate or use DA+AD during Blood Price runoff. All of those require non-standard usage of Dark Arts. If you're not innately aware of these rarely-used effects, you're flat out not gonna do it.

Which results in DRK being squishier than PLD and WAR in trash pulls, in general. DA+DP/DD/AD is way trickier than "having a shield" or "hitting bloodbath" to be quite honest.