But we all say that "well two million people read the daily mail and my friends read the mail so they would identify me on there but not on mn," but reality is that we can't know that for sure. Do you know where all your friends post? Do you know for certain that your friends don't post, or at best lurk, on mn? The people I know in rl don't know I post here (well that is to say I haven't told them that I do), so for all I know they could be reading my every post, and from my postings I'm fairly identifyable so it wouldn't be hard for them to keep track.
I think people are too sure of themselves when they say that people they know in rl don't post, or read mn. Perhaps they don't, but all they have to do is google one day, and for something to ring a bell with them, and voila, they have a whole posting history they can look back on..