To be fair, if you remember only the main events of any story, it's not difficult to recite it from memory. For instance, I've read the Lord of the Rings trilogy many times. I had no problem reciting the entirety of it to my grandmother after my first read through. You may think that a story recited this way would be shorter, but it's not difficult to improvise or embellish. The Odyssey has an extremely simple plot by today's standards. It's been quite a while since I've read the book, but I'm pretty sure I could skim through the cliff notes and tell a pretty compelling version of it.