There are many different kinds of decks that want to run cards with proliferate
This deck was already a fringe deck in Modern, but Oath of Nissa might be exactly what it needed to propel itself firmly into the sphere of competitive Modern decks, especially since this is another deck that can use the recent big mana offerings well and might want something like Ulamog, the Ceaseless Hunger or even World Breaker, both of which, of course, Oath of Nissa can help find when you need it, giving you a different sort of flexibility, offering a card that does what others couldnt
Vivi is an extremely scary Commander to boot
Plus they provide card draw from the command zone
Sure, red has Warp World and Bazaar Trader effects to give away zombies, but without black, there arent many ways to help Daryl do more of his thing
Furthermore, many of those are very niche cases (save for one of Urza's Destiny's most valuable cards, Yavimaya Hollow)