Social change takes trust. You trust the thought leaders of the movement, you trust some set of information around the issue, you trust those who work with you to support you and not to expose anyone to undue risk.
Social change also takes privacy. If you are really pushing boundaries, you are at risk - of physical violence, imprisonment, or worse. There's value in being very public in this space as well, but that doesn't mean there's not a stage where protecting yourself through some layer of privacy is a better plan.
Social change also takes voice - citizen media platforms, and use of existing social networking sites which already have global scale and the ability to amplify a message.
Unfortunately, there's a lot of bickering around privacy, pseudonymity, and social networks - Facebook naturally, but even Google Plus is blocking pseudonyms from using the site reliably. I got tired of re-hashing the very valuable differences between using one's own name, being completely anonymous, and using a pen name - a well-storied way of getting an idea out while saving one's own neck: