First and foremost, I don't want a Twitter. I dislike most websites that fall under the heading of "social networking." Also,
I don't care what I do all day. If I were doing anything interesting enough to warrant frequent documentation, I wouldn't have the time.
Sometimes, though, I think about what I would write in my hypothetical Twitter. Or something will happen, and I'll think it's just the sort of thing I would Twitter about. You know, stuff that's not really blog-appropriate. I thought about compiling some of these things, and making a blog entry about Things I Would Have Twittered, but I never actually write them down, and then I forget about them and no longer care.
Furthermore, while I may want to write these things down, I don't exactly want people to read them. I don't want people to follow me, I don't want to follow anyone, I especially don't want to follow anyone famous, and I don't want to be in any way connectable or findable. (I totally Googled some people I knew in high school yesterday.)
On some other hand, though, Twitter would provide a great venue for cryptic one-liners.
And those are my favorite. I would be utterly delighted to give my inscrutable gibberish as little context as possible. I am positively itching to let you know everything while letting you know nothing!!
... It is not and has never been a mystery why I have trouble socializing.