more so for Scattershot. Aim in a direction of any character that's a squishy and it kills. I can kill so many guys just aiming in general direction with it. I don't pretend I'm a Hanzo pro because of it.
None of the other projectiles have the property of bouncing off half the map to hit you, though.
If that's how it's being used it's not really different then junkrat or pharah spam. Shoot into the choke point or hallway or whatever hoping to kill someone isn't really anything unique or special.
Using any of those projectiles properly does take a bit of aim though.