It's too cool to lose forever and Guardians finding a way to summon the Scythe on their own would immortalize Guardians victory over the Pyramids Nightmares. When i look back at most expansions, there was some kind of power that we learned to help us take on the new threat. In Taken King, it was the 3rd subclasses. Forsaken there was the new supers and nodes. In Beyond Light it was Stasis. In Witch Queen it was deepsight. There was no power that really defined Shadowkeeps story until we we channeled nightmare energy and light into the Scythe in Haunted. It would really give a whole new meaning to what it means to be Reaper in Destiny. Something that the Pyramids will see and figure "Ok. These guys are very strong against psychological attacks and will reap and turn our power against us if we try." An ideology and a weapon rooted in Light to gain strength from trauma.