I might be a special case but I signed up for Twitter just so I could keep an eye on who is tweeting about my company and make an occasional reply. I don't follow anybody and wouldn't have finished the signup process if I was forced to follow someone. I find it a pretty great solution for real-time customer service, both as a founder and as a customer, but I don't want to hear everything anyone has to say unless they're a good friend of mine and in that case they are on Facebook. For notable people, if I care at all what they have been up to I will go to their blog, and for a real-time event I will simply search for it on Twitter.

The awesome thing about Twitter is they let me use their service exactly how I want to and don't force me to do anything else, like randomly click 5 topics I couldn't care less about. I wish Quora were similar in that respect.