Not to be a broken record, but I think these accounts are setup to "listen" to the brands, people, celebrities, products, etc that the subscriber is interested

Not to be a broken record, but I think these accounts are setup to "listen" to the brands, people, celebrities, products, etc that the subscriber is interested in. Most people don't blog, but lots of people read blogs. Twitter isn't really a social network, it's a subscriber broadcast medium.