One of the primary objectives of any blogger should be to build a blog community, people who are interested enough in the topic of the blog to register that interest and follow the blog. Otherwise what would be the point of writing and publishing a blog on the Internet that potentially no one ever reads.
Some bloggers do want to restrict their blog to private members, friends and family which can be done by restricting the access of the search engines and marking the blog private access only, so the blog community in this case becomes more of a private club than a public house.
