We all thought, like the author, that access to the Internet will put people in connection who otherwise don't hear from each other, that we will be exposed to new views, be more open-minded, etc. And the opposite has happened. We forgot that the traditional barriers to intercultural understanding are still there: language, tribal sentiment, political and economic power structures, etc. At the end of the day, in a democracy the majority can do anything it wants, even if what it wants is to punish the minority. The Internet has had all the failings of a total democracy in that sense.
I also love the point the author makes at the end. Silicon Valley loves to think of itself as a bastion of rationality. But like every group and every ideological movement and every person, it has a set of core beliefs taken on faith and not on evidence. It's very possible that the core beliefs and faith on which the Internet as a radically open, radically free, nearly anarchic space was founded, are...wrong...