Reason number 3: They're so self-important

Chris Alden discusses what happens when bloggers' rights are infringed.
Now, if I work for a business and spend my weekends putting signs up around town discouraging people from using their services, or deliver regular speeches to that effect in a pub, or use any other means of publicly and indiscriminately communicating my distaste for my employers, I would expect to be disciplined at the least, and possibly sued for slander or libel. If I do this sort of thing on a blog (which is a saintly process no one would ever use to settle a score) then it would seem I can rely on a special privilege, under which it is my rights which are in danger, and not the rights of my employer to go about their lawful business without unaccountable attacks being made on their character.