The Graveyard acts as the final destination for the normally immortal divine. A hell for the petty and small minded deities of old who either perished by any means or were forgotten by their followers. It was the ultimate resting place for all their kind until said gods found a means of returning to life in another form.
The Graveyard of Gods is a malefic place that feeds on the negative energy of the dead's actions in life. Time spent their causes their ire and spite to boil uncontrollably, driving its denizens to the brink of maddening fury.
Its presence within the Multiverse also served as a seal through which two more of the 7 hidden forces linked to the Totality were sealed behind. As with the proverbial mortal Underworld, it had its own three-headed guard dog to watch over its prisoners.
Not only would the destruction of the Divine's afterlife mean releasing these energies into the wider reality, but also meant the oblivion of any more deities should they perish. Meaning any god who was dead and trapped there or died at any point in their lifetime, would end up dead and gone forever. Their souls disappearing into primordial entropy.