In the ancient world—long before printing presses and the world-wide-web—most people didn't have the opportunity to learn to read and write. Education and literacy were the privilege of the few—mostly the wealthy.
Even today, much of the world's population is non-literate or has limited literacy. God in His great wisdom instructed those who wrote the Scriptures (2 Peter 1:20-21) to write in a memorable way—using stories and parables and poetry with lists, alliteration, illustrations and other forms of figurative language.