Oh absolutely!
But that's not really constructive because you could say the same about 99% of social-network businesses, no?
You could also say: "It's not always the physical structure of a country that makes it great but its people (culture, history, how it started, so on) " and that would be true too. The fact that different websites have different 'cultures' make all the difference, right?
I like the artificial 140-char limitation though, but it would be comically easy to enforce it anywhere else.
There is always another social network: Reddit, Usenet, Forums, IRC. Twitter is a place where we have conversations for now, but the "innovation" of fast-paced conversations can exist anywhere... and already exists anywhere.