The embodied anguish, gloom, misery, etc. from the desperate measures phases are all targetable and within range before pulling the bosses and attacking them does not cause the bosses to engage. The mobs appear to be floating too high to hit but because they are tied to the actual bosses their hit boxes are close enough to be engaged from the ground. This is a great way to build up secondary resources for the ranged DPS in your raid during progression prior to each pull