Yes, but tweetchains are notable in that they're exceptions to the normal flow of chatter on twitter. And a good tweetchain will have people retweeting-out the good parts.
Should every site be twitter? Hell no. But is it a good thing that one or two major social media sites demand brevity and distilling your thoughts? Yes.
A different thing, certainly. An interesting thing, probably. A good thing? Just because something is different and interesting doesn't mean it's good. Twitter exists as a site on the internet, which is probably the most charitable thing that deserves to be said about it.
Should every site be twitter? Hell no. But is it a good thing that one or two major social media sites demand brevity and distilling your thoughts? Yes.