I agree with you completely regarding privacy. If you feel that you must absolutely prevent some piece of information from leaking out into the world for all to see, you must treat every communication medium -- and the Internet specifically -- as insecure. The world is littered with dead political careers of people who did not heed this warning.

That said though (to paraphrase the old adage), are we rationalists or are we mice ? If you hold some beliefs that can get you burned at the stake (figuratively speaking... hopefully...), then isn't it all the more important to determine if these beliefs are true ? And how are you going to do that all by yourself, with no one to critique your ideas and to expose your biases ?