It's not literally every thought; ideally it's only the best/most interesting ones.
I rather enjoy seeing what's on the mind of the smartest people in the world (and even moreso what they're reading), and that's what I try to structure my Twitter feed for.
I try to tweet things that are at least somewhat insightful, but maybe I really suck at it. The great thing about Twitter is that if people don't think I'm interesting they can unfollow me. I really love that. Being on Twitter is like being in a room with whomever you would like to at any given time.
Well its usually unappealing, doesn't mean always. Look at it this way - would you tell the world to stop writing so many books unless they knew the book they were writing was a bonafide masterpiece?