There is many DH problems. But 2 of them are dependant on the other, theres 2 routes to fix it.
On one side, spells of DH looks to be doing correct damage coefficients. Some of them just cost way too much. They just have terrible mechanics or next to no practical use in the meta game. Look at cluster arrow, look at how shit that thing is compared to HotA or WoL. It does less damage then either of these, cost more ressource, oh and best of all its radius and way of use is just pure shit.
So if you dont fix the shit ass mechanics, you gotta buff the damage, DH has nothing that stacks togheter like others. The best DH can do is stack Spike traps echoing blast and spam bola shot at the same time. Its still not close to the damage A HotA barb like me can punch up or a good monk, My rend crit ticks for more then a DH bola shot can crit in the same gear. My HotA hits for more then 6 spike traps ever could. Because im buffing myself to 400kpaper dps when im in combat. Even if that DH had straight 400k paper dps he does not get close my my kill speed. I know one of my best friend is a DH. I personnally left the class after they nerfed inferno and farming became so easy, DH was only good to finish inferno in the first week of this game.
Passive like Shaprshooter and Steady aim looks good on paper, but they are just pure shit. There is very little synergy in DH passives unlike every other classes. Even WD has some crazy passive synergy to pump up some massive dps with the correct gear.
The last problem, Healing for DH is an aboslute chore and literally forces every single DH build ever to use Shadow power gloom, you cant have a build without it and farm any high MP. If you do you are an idiot, thats what the game is telling you. Why is that? No its not because Shadow power gloom is OP. Have you ever tried to get Life steal or loh as a demon hunter? DH gets by far the worse coeficient of healing. LS because of the low damage, look at the huge LS from shadow power, i get better life steal tick as a barb or a monk with 6% lol. Dont even get started on LoH, DH spell has the worse coeficient out there. To have any meaningful healing a DH needs 15% LS from gloom, its not possible to survive with anything less.
All of these problems could be fixed with some rebalance, ei: give DH better healing coeficient on spells, change one of the trash passive to LS (Brooding lol, im regenerating 1% of my life per second useful lol!). Reduce hatered cost dramaticly or update the damage to match other classes expensive moves or make their mechanics not suck.
To anyone telling these DH they are not correct to ask for help, get the hell out of here. DH is pretty much the only class that is not optimal to play in groups at high MP. You dont want the DH there at all, hes just slowing you down compeltly. Give me a Sac WD or Zombie bear. Hell next patch give me an archon wizard, anything produce more damage or brings more useful buffs. That is why they need help, if you cant understand that then stop posting in this thread.