DPS Enmity controls

[Megguido]

That's incorrect. If a sam uses merciful eyes instead of seigan. That's a loss of 200 potency.

Apparently monk is in a similar position it's enmity dump is a dps loss. As it eats chakras or something

That's also incorrect. Seigan is 200 potency but requires both open eyes and 15 kenki. Seigan is a slight DPS gain over Shinten (13.3 potency/kenki for Seigan instead of 12 for Shinten). It's less than 30 potency lost. Dunno for MNK though.

I think Lilyth's point was mostly about Diversion, which costs nothing but a role skill slot, and reduces a lot the aggro needed from the tanks. And if tanks don't have to use tank stance and threat combos, it's a raidDPS gain.