Journalist and New Yorker writer A.J. Liebling is credited with the aphorism: “Freedom of the press is limited to those who own one.” The quotation is frequently cited by those who argue that America’s vaunted civil liberties, freedom of speech and freedom of press, are not as expansive as they seem. Anyone can speak from a soapbox or distribute leaflets, of course, but reaching and influencing a significant number of people requires owning a major newspaper or radio or television station—something that can cost millions of dollars. Thus freedom of the press, some argue, is a luxury only the wealthy can afford.

However, the advent of the Internet and the World Wide Web has changed this, according to some media scholars. For little to no cost, people can post their observations...