I love that Moana idea - it strikes me as very Curse of Chalion-esque, where Moana is not the only one called, or even the only one who set out on the quest, but the one who finally completes it.

It rings true that the Ocean was being very judicious about when and where it helped. Ultimately the problem was a spiritual one, and to solve it, Moana needed to take her own spiritual journey, which the Ocean could facilitate but not force.