Anonymous blogs are one answer the relatively powerless have when speaking what they believe is truth, to power.
Power is typically governmental. So it was when the help of the Electronic Frontier Foundation was required to help an anonymous New Jersey blogger, "datruthsquad," face down the township of Manalapan when it sought to unmask him in 2007.
Sometimes power is corporate. The corporation may be, as we see in the confrontation between First Baptist Church of Jacksonville, Fla. and FBC Jax Watchdog, a church. In every case, some risk attends attempting to say to power things it would prefer not to hear.
As gwfrink3 documents, not all serious, careful bloggers who come under direct fire from the powerful emerge from it in good condition. That's why it is important for anonymous bloggers to attend to the technical details of their anonymity.
The Watchdog has not gone public with his name, receiving a great deal of criticism for blogging anonymously, but explained to me he remained anonymous out of fear of retribution from powerful civic leaders who are members of the church and could intentional[ly] seek to ruin his name and business. He told me his compelling story, details of which are startling, because he said he trusted me.
Matters may not go that far, but thinking ahead and guarding against any number of possible unfortunate possibilities is simply due caution.