Marshall McLuhan said: "The medium is the message."
The first technology that was applied to communication was that of writing. It started with marks on stone or clay and then progressed to ink on papyrus and parchment. Communication changed dramatically from being spoken words with the context of relationship to voiceless words without human connection. Anyone who could read had access to the words that were written and could move forward with them. Learning wasn't limited to the human memory and what could be passed down from a master to an apprentice. Over the course of thousands of years, humanity was able to develop a body of learning that encompassed science, mathematics, astronomy, politics, literature and religion. Without the simple tools of writing, the pursuit of learning was limited.
Script communication, however, communicated something apart from the words on the page. It communicated the power of those who could afford the scribes and the libraries over those who couldn't afford to read and write. The wealthy could afford to learn, which gave them more opportunities to earn money, which increased their ability to devote time to learning. For the majority of the history of written communication the literacy rate has been in the ten percent range. Learning to read and write wasn't a luxury afforded to the poor 90 percent.
So, power accrued to the powerful and poverty increased among the poor. Writing didn't change the state of things between the two groups. The rich saw nearly all of the benefit of learning and communication, but the benefits could only survive so long as the rich could maintain power. A glance at the drastic changes in medieval Europe is enough to show that the progress gained by the Romans was soon lost when the illiterate tribes overthrew the Roman rule. Europe, by and large, was lost to all learning for centuries while the Middle-East added to the learning of the Greek and Roman scholars. The continued stability of the powerful in the Middle-East allowed for the benefits of writing to continue, but the Europeans lost nearly all of the progress with the loss of the ruling Romans.
It wasn't until the writing came back to Europe in the Renaissance that they began to lead the world in learning again. But that is the story of the printing press.