The World Wide Web is the most democratic mass medium there has ever been. Freedom of the press, as the saying goes, belongs only to those who own one. Radio and television are controlled by those rich enough to buy a broadcast license. But anyone with an Internet-connected computer can reach out to a potential audience of billions. This democratic Web did not just happen. Sir Tim Berners-Lee, the British computer scientist who invented the Web in 1989, envisioned a platform on which everyone in the world could communicate on an equal basis. But his vision is being threatened by...