Not sure what are simple oral traditions, but the Vedas [1] are oral transmitted. To preserve meaning there is elaborate chanting techniques. They have been written down recently, however, to really learn them, one needs to chant. They are pretty complex for sure.
If the Vedas oral tradition "led directly to complex story-telling literature," you may have a fair point, but with only the example of the Vedas having a complex oral tradition, this (as a candidate for counter-example) isn't exactly clear. But I'm almost certain there's tons of complex stories in mine and especially in other cultures of which I am not aware. If there wasn't, maybe I could give you a hand.
Hindu tradition state that it directly led to elaborate literature and rich story telling. Puranas [1] and epics like the Ramayana [2] and Mahabharata [3] were orally transmitted as well. The point being that the Vedas are pretty terse which makes it hard to understand or apply without specialized knowledge / background. The Puranas, Ramayana and Mahabharata provide context via stories etc..
1. https://en.m.wikipedia.org/wiki/Vedas