No Reason.
(…) described by the phrase coined by the media theorist Briggs: “the conservative dilemma,” so named because it applies not only to autocrats but also to democratic governments and to religious and business leaders. The dilemma is created by new media that increase public access to speech or assembly; with the spread of such media, whether photocopiers or Web browsers, a state accustomed to having a monopoly on public speech finds itself called to account for anomalies between its view of events and the public’s. The two responses to the conservative dilemma are censorship and propaganda. But neither of these is as effective a source of control as the enforced silence of the citizens. The state will censor critics or produce propaganda as it needs to, but both of those actions have higher costs than simply not having any critics to silence or reply to in the first place. But if a government were to shut down Internet access or ban cell phones, it would risk radicalizing otherwise pro-regime citizens or harming the economy.
Clay Shirky: The Political Power of Social Media