All DPS are selfish.

And I wouldn't call RPR a selfish DPS since their raid buff has to be used to even use PH alongside having a low CD weak shield that gives the party a HoT which they probably should of kept if their damage is going to be as low as it is.

And to get the most bang for your buck the whole party has to hit something to get a full power PH.

Reaper is very middle of the road and is very reliant on Enshroud/GibbetmahGallows for it's damage. Otherwise it's a wet noodle.

You can also make the argument that Reaper probably has lower damage because it suffers from ranged tax because it can Harpe from a distance and warp in and out of bad situations if it needs to.