For someone like me that only push mythic+ using my own key, i kinda agree with the statement of majority of dh is terrible.
Some even can’t get their spell rotation right, doing terrible damage, sometime i could just even or out damage them as arms warrior.
Some didn’t use their abundance of utility in mythic+ to smoothen the run, for example didn’t incorporate chaos nova into spell rotation to cc those dangerous trash pack. Use imprison on some dangerously positioned emissary or mobs.