I actually got banned for a day for "over-replying", not to one person mind you, but just in general. Replying to peoples tweets is apparently disruptive, funny as I thought it was the point and that I was participating.
It's a social networking site that doesn't encourage social behavior, unless it pleases, and puffs-up the poster.
The site is ridiculous as anything but a corporate announcement site -- and this is why it's going to ultimately fail. My guess is that it will be dominated by "news" and product marketing more and more each year until it's irrelevant.