I think one of the greatest ironies is that the people who envisioned the world wide web like Douglas Engelbart, Alan Kay, Ted Nelson, and Tim Berners Lee really intended that it would be a tool of mass education and in Nelson's case actually mass liberation for people, because publishing would no longer be the tightly controlled chokepoint for information and the democratization of knowledge would be a self reinforcing bulwark against government and corporate propaganda (consider that at the time, people like Saul Alinsky were interested in the problem of having adequate channels of communication among radicals). And while that's true, it also turned out to lower the cost of propaganda and disinformation to zero. In the past, if I wanted to read communist literature, I had to go to the right bookstore that I only found out about at the right university. Or your crazy friend Bernie Sanders who had a honey moon in the soviet union lended you his annotated copy. Now YouTube has an algorithm that automatically services you with the things which are most likely to reinforce your beliefs. And Twitter, etc.
This is pretty much exactly what Neil Postman meant by how all technology had serious unintended consequences, even consequences opposite of original intention, and the internet should come with a surgeon general's warning.
It's not like it was totally unforseen, though. When Bill Clinton was pimping the internet, he'd say something like "this will give us thousands of new TV channels to choose from," to which the natural, thinking reply is "do we actually need that?"
