Why does Twitter still exist?

I joined Facebook a few weeks ago. You may have noticed by the lack of posts. Immersed in the wondrous array of converesations, photosharing, games, and microblogging, I forgot the real world existed.

But my experiences raised a question: Why is Twitter still around?

I used to use Twitter. A lot. I'd post 4-9 tweets a day. Since I joined Facebook, I've visited it once. That visit was to delete my profile.

Facebook offers everything Twitter does, in addition to hundreds of other things like photo hosting, games, scheduling, and friends. It also offers it better: while posts are still constrained in length, they are nowhere near as short as Twitter, allowing intelligent posts which are impossable to convey in 140 characters. After posting for the first time on Facebook, I felt how Winston Smith would have felt had he been plucked out of 1984 and dropped into New Atlantis. I felt freedom in a way that was never present on Twitter. I could actually speak my mind.

Facebook also offers so much more then Twitter: An excellent photo sharing system, a way to embed photos and video into posts, games and quizzes, and most importantly, social interaction. It's all optional; in fact it is quite easy to use Facebook like Twitter. But the opportunity to make friends and have fun are still there with Facebook, in a way they weren't with Twitter.

The social interaction is the biggest thing for me, as it is for most who use Facebook. I can post saying "I'm going to the movies. Anyone want to come?" and others can comment directly on the message. No more digging through hundreds of tweets. All the things that have to do with my post are grouped with it. Also, Facebook offers a good IM system built into the site, with no download needed. When you want to talk privately and immediately, you can.

The photo hosting is good too. Although the images are only moderate quality (you'll have to use Picassa or something like it for high quality), the get the job done. Also, they're easily viewable to your friends, with the added bonus of friends being able to tag themselves in your photos. All in all, it's really good for something that's free.

Also, no porn. No spam. On Twitter there is a constant stream of spamalicius drivel friending you, and there's nothing you can do about it. Yes, you can manually remove friends, but the damage is already done. Even if only for half an hour, you were listed, for everyone to see, as friends with "sexnow1234". Have fun explaining that to a college admissions board.

Speaking of which, the privacy on Facebook is amazing. On Twitter, even if you set your account to "private", everyone can still see your posts. On facebook, if you're not a friend, you can't see anything. No info for stalkers, no ammo for haters. It's your decision who you trust with permission to your page.

So, let's review. Facebook, is more useful, less constrained, more private, safer, and much easier to use then Twitter. Why does Twitter still exist?