I think useless is an exaggeration. In terms of damage a single-target Patchwerk fight, I think it simulated a bit behind DS. Given that DS provides better mobility and more flexibility about when you spend your fury, it's a much stronger spec overall for most situations.
But one situation where I think people do find it useful is Blast Furnace - where you have small adds that you need to burn down quickly.
Demonbolt was brought down so it's damage is comparable to other specs (as opposed to being way ahead of it) - so there may be niche cases where it comes in handy, although other than Blast Furnace I can't really think of any...