I mentioned it made a difference in the current Nightfall. Specifically, there were 2 areas that it was essential.
The first part is where you have to defend Ghost from the waves of Fallen. The Fallen spawn from 2 corners of the room, and if you see a big pack of them piling out you can kill most of them with 1 shot from that thing. Have a person responsible for each side of the room and the 3rd person helps as needed, whichever side is getting overrun, otherwise they mop up the spear guys who stealth into the circle.
In the boss fight, once you get the boss down 1/3rd health the room starts spawning lots of fallen. It’s not as easy to wipe a bunch of them because it’s so chaotic, but you can still mop up big packs of them with that launcher, especially around the servitors. Alternately, equip a shotgun or Merciless as your power weapon and just go hard DPS on the boss when he appears.