Stick with me here. As you may remember, I have like, maybe 7-10 friends that I follow on twitter (and some people that I follow but don't know personally). A few Sundays ago, I was at the Magic tournament after church, and I texted the following to twitter:
Switched decks minutes before match 1 and glad I did. Went 2-0 v time warp deck w my crappy red deck. Other matchups look hard. Expect 1-2 overall[incidentally, I went 2-1]
Now, how many people on my twitter friend list care about that, much less understand it? I would say 0. Yet, still I kept Twitter posted with periodic tournament updates.
I think one reason Twitter is popular is that it's basically like always having a friend to text that cares that you are eating pancakes for breakfast two days in a row. Twitter is up at 4am to hear that you don't feel tired. Twitter is there to hear that you don't like waiting in line. Twitter is there to tell funny things that happened during the day. When no one on your Twitter friend list would care, Twitter wants to hear more of your stories.
Edit: as Val points outs in the comments, despite being mute, Twitter has no problem broadcasting everything that you're up to to the whole internet and potential employers.