Leaders are scared of powerful media. Controversial ideas and criticism undermine their authority. Censorship is an effective weapon against deviating opinions. Nowadays, many countries do not have freedom of speech. Political and religious rulers reduce the (social) media to silence.
In the sixteenth century, governments drew up a list of prohibited books to nip discussions in the bud. Printers were creative, however. Critical texts were produced illegally and distributed via underground networks.
Patents gave printers exclusive rights to publish certain titles. Some sought refuge in piracy. Without permission, they reprinted popular books on which somebody else had the monopoly. Illegal distribution of films and music is big business today as well. And people keep finding ways to bypass internet censorship.