In 1936, Walter Benjamin published “The Work of Art in the Age of Mechanical Reproduction”. It’s a moderate-length essay on a variety of subjects related to the practice of art as its production techniques have evolved. The following is still relevant today, in the age of internet comments:

With the increasing extension of the press, which kept placing new political, religious, scientific, professional, and local organs before the readers, an increasing number of readers became writers – at first, occasional ones. It began with the daily press opening to its readers space for “letters to the editor.” And today there is hardly a gainfully employed European who could not, in principle, find an opportunity to publish somewhere or other comments on his work, grievances, documentary reports, or that sort of thing. Thus, the distinction between author and public is about to lose its basic character.