0) Your arguments seem to be targeted at social media in general (eg. why I can't follow them on their sites, etc). Don't want to get into a conversation on benefits/disbenefits of social media
1) There was nothing in my comment to imply that my friends were from the U.S (they are not), but as I said, the user growth could be just for me.
2) >Why can't you follow the experts... Twitter IS their online community. As everyone has mentioned, it's like RSS, where everyone is, and they let me know when their 'communities' are updated. Because I wouldn't want to check a hundred sites every day.
3) A tweet is 140 characters. All large tweeters post texts as images to get over the limit. People often engage in multi-tweet conversation. The 140 char limit is useful there because twitter shows how many tweets the user has in the conversation. If you're not interested, you don't encounter a wall of text: you see a tweet, and then bail out. Subtlety is lost in 140 characters, but if both parties are looking for a fair conversation, they usually engage in multiple tweets.
4) I do indeed use twitter to bookmark. I also use twitter as RSS. And to get to know people I don't know and follow them too. As a public social media. You could also have Googled 'arguments for and against twitter' and be done with this entire thing, but you chose not to. : ) Twitter is a community, and that's what people are there for.