[DoreenMichele]

I can be identified. And until very recently, if you searched under my legal name, you found little or nothing about me online, never mind that if you knew where to look, there was ridiculous amounts of information about me online under various forum handles and blogs.

If you have really serious fame of the sort that means millions know your name, you may find it hard to obfuscate your activities. If you are doing something so bad that some government wants your hide, yeah, they may find you.

But for most folks who just, say, don't want their "respectable clients" to know their porn habits or something like that, having a nickname that your friends know you under separate from your "public"/professional identity can have loads of value and can be sustained for a lot of years without much effort at all.