Internet does have many desirable qualities as a medium for public discourse, but nonetheless there are also some less attractive features. One of them is the total control the publisher exercises over his message, and that means he can change it over time without any notice of the change or manipulate it to fit a particular audience or even exclude some audience from receiving the message. To make the point more clear I created an example - a simple web page that publishes three distinct messages to readers according to their IP address. One is praising Microsoft the other dissing it and the third I won't disclose here.
This total control was not available for print or wireless media. TV and radio stations emit the same signal to all receivers, the same with printed papers. In the print case the printed paper was additionally a proof of what was really published.
Update: Detecting Cloaking in Web Pages