Many blog owners use article directories to get content for free. This helps the article directory owner as he gets more customers for his paid services as he has a large distribution network. The blog owner gets free content, which may be monetized using PPC or CPM advertising.
However, the blog owner is free to delete the content on the blog as they wish as they do not receive any payment for it. This is not known to most internet users who do not have any blog or website of their own.