blog on blog

yup I'm gonna be that guy,, writing a blog on blogs. but seriously, what is the deal why are blogs such a big deal. I supposed that it is a extremely easy why to voice opinions and give information but really why do people care all that much about what I or anyone else has top say about ads or whatever. I think the only reason why I am negative about blogging is because recently I was told that portfolios without blogs are more likely to be discarded that portfolios with blogs or links to blogs. What is the deal? How are blogs important to portfolios all of the sudden, especially if no one reads them. If someone could explain that I'm all ears.