There's a few factors at play. To name a couple: 1) A lack of ability to outsource memory to the written word. I forget who it was, but either Plato or Aristot

There's a few factors at play. To name a couple: 1) A lack of ability to outsource memory to the written word. I forget who it was, but either Plato or Aristotle was famously against writing because they said it would degrade human's capacity for memory (and "learning" if I recall correctly, though this was arguably wrong). 2) Perhaps even more importantly, the content of the time was shaped to the available medium. It's no accident that epic poetry from the oral tradition universally contains huge amounts of redundancy and pattern: meter, repeated adjectival phrases, character epitaphs or titles, etc.