Even though CoH was the game that broke the Holy Trinity of Tank/Deeps/Healer, the devs still thought along the lines that any 'difficult' content would need different roles fulfilled. You still needed to grab aggro and hold it. You still needed healing or status mitigation. And you still needed damage (and lots of it).
They didn't think about what would happen if a buff/debuff heavy team took on ALL of those roles simultaneously, healing each other, lowering target stats to the absolute floor, and raining out a ton of damage all at the same time. You don't need a tank if the mobs can't hit you hard, you don't need a dedicated blaster if resistances are floored and to-hit is buffed to the cap, and you don't need healers when everyone on the team can heal. And with the FFoF runs, using unlucky (or unwitting) characters as sacrificial lambs for Vengeance/Fallout was just icing on the cake. "No, stay down, don't port off to the hospital, we'll just TP you around and use you as a bomb." has to be one of the silliest and yet most fun ways to get PL'd in the history of MMO's.