I'm sorry, but I think you have it backwards. You're right that PLD feels like a protector, but you don't realize that the one person who really needs protection is, in fact, the MT.
If you're the MT, Intervention and Cover are not really that useful.

Problem is, the MT/OT is not something that should be enforced, because any setup should be as viable. What could be done is having different ways of staying alive, but SE had a hard time pulling it, so all tanks focus on reducing damage.