Todays patch might be fine-tuning the zone. The piece from PoEarth for the quest bow is ridiculously scarce given how many people need the item to advance. But it wouldn't surprise me if they tune down the mobs and raise the diamond drop rate as well. This is classic Sony, releasing a high-end zone and making it far too hard and then partially "nerfing" it after getting a lot of reasonable complaints from players.
No reason it shouldn't be groupable, at least in part, since it's not a pure raid zone, at least not the intention from what I've read.