Imagine this with Commander Eesha in play, as one example
Thats cool, but theres more
Functionally, Yuna's Whistle is a pseudo-cantrip that always replaces itself with a creature, and finding the creature gives you some +1/+1 counters too, so there's combat trick potential as well
Proliferating first means every planeswalker, creature, or permanent with counters gets stronger, then those permanents phase out, dodging almost any removal or wipe until your next turn
However, thats very clearly what Rielle, the Everwise is designed for
This basically boils down to Jund and Esper looking much less consistent and put together compared to the other two decks, although this might be (at least in part) because it's easier to build a cohesive artifact- or enchantment-themed deck than more abstract themes like "the top of your deck matters" or "lands matter." Here's a quick pros-and-cons list on the four decks