Actually Benedictus could be good if Void Contract saw any play.
I would argue, that Archbishop Benedictus has been always good. He gives us more juice and delays the fatigue - this makes him a good powerful value generator for control decks. He was used in quest priest last expansion. I think the reason why priests don't play him in standard anymore is because they prefer to have a better win-condition (Mecha'thun). This is my personal opinion, I don't know if this is really the case. Archbishop Benedictus is only bad against aggressive decks, since you dilute your deck there and you might not get a powerful board clear on time. Speaking of which, priest lost a lot of powerful AoEs after the previous rotation so the class got weaker in general.
Before Void Contract there was (and still is) Rin, the First Disciple. Benedictus can be used after the warlock plays Azari, the Devourer. I am also skeptical that the warlock spell will ever see play. Outside of a combo meta, this card is really punishing. While warlock CAN refill his deck again (w/ Glinda Crowskin + Baleful Banker), we can't revive the strong cards discarded this way. Let's imagine how we lose our DK - bunch of 2/2s and 3/7s can't compensate the loss. So there won't be any danger of this card becoming popular (unless warlock gets a card, that shuffles all destroyed ones back into the deck, but such an effect would be super OP; and unless we are in a heavy combo meta).
Benedictus didn't see any play vs Rin because there wasn't a reason for him to be honest, rin is so slow and she will only burn 4 cards or so, this wont justify running benedictus, but Void Contract is a single card, and can be played in turn 2 using BloodBloom, benedictus and Spirit of the Dead could help priest counter Void Contract ( if it saw any play )