Dismantle/Reprisal are often up for heavy raid wide AOE. Take Sus ex's Ukehi, Lakshimi ex's Strotom, O1s's Roar or Blaze, O2s's Gravity waves, and O3s's Dimensional waves, O4s's Almagest. Dismantle can help mitigate nearly every one with a 1 min Dismantle CD. And do I have to repeat myself, it STACKS with reprisal for 20% damage reduction. In fights like that where damage is absolutely insane, someone may not be topped off, and it saves raids from wipes. I have seen it many times.

I am not arguing that MCH support is better but Dismantle is most definitely better than Troubadour. The only time I think Troubadour can win is in long continuous damage phases. O4s soft enrage for example is actually the only time I can think of. A8s soft enrage too I guess. Otherwise Dismantle is extremely versatile and can mitigate 3 heavy hit/tank busters in the same time. Tanks having it has nothing to do with it. That means more mitigation. Since it STACKS.