Everyone else has answered the question, so I'll just put my two cents in. I find myself locking more and more posts, simply for privacy reasons. If I'm bitching, or relaying some personal information about myself or my life, or posting something that I think others might find silly, I lock it. It just makes me more comfortable. However, I have had the same thought that you have and worry that someone who might want to friend me might go and look at my journal and say "She never posts much!", but you'd think that anyone who was familiar with LJ would realize that you might just be f'locking your fandom posts, or whatever.