He is trolling you guys, trying to rile you up.
DRK is good at making SC's due to it having many different multi-hit options. It's important that the WS selection be multi-hit because it avoids fudo-syndrome.
For pure damage, DRK is suffering pretty badly. One is that 2H WS's have their FTP too low compared to all the 1H WS's, and unlike WAR, DRK can't just do a Fencer build to exploit high fTP scaling. The second area that is hurting DRK is accuracy, DRK really got shafted in the acc department, even more then the other 2H jobs. The recent release of valourus gear and the updates to Emicho / Argosy helped this somewhat, but in return it severely limits the gear you can use on WS's since you need to maintain that high accuracy.
Outside of those two problems, DRK suffers from the same problems that other non-BLU/DNC jobs suffer from, needing additional support to optimize their damage. BLU's and DNC's can each apply additional haste to themselves and / or others and thus require one less support then DRK/WAR/DRG/SAM/MNK/THF. Today we need to stuff as much as possible in a six member party due to the obscene HP scaling system SE created. Bringing more people only makes things harder, and thus we are now looking to pack as much into each individual slot as possible.
Should SE fix some of these issues, lesson the obscene accuracy requirements and raise the fTP of 2H WS's, then we could see different melee jobs used more often. And this is without even going into the blatant abuse of broken BSTs and SCH SC's.