Because i have seen a destroyer wowing down a dozen people in 6vs6 never stopping spinning, every time i tried to get near him and use KD the spin glowed red again and he was immune.
I could SS out once but because of the bonus movement speed he cached up and all i could do was stand in there stunned, dying, Attacking him is pointless as melee, you can only run away which is simply stupid, if you run away he jumps on you, great.