I think, in our days and age, blogging serves more as a writing exercise than it does as a way to disseminate knowledge, strategies, information, or lifestyles.
The only way to improve one’s writing skills is to write, and blogging is as good a way to do it as any.
The only great issue with blogs with no traffic is the lack of feedback and validation. Even if you tell yourself you write for your own sake, for practice, for developing your skills, the absence of feedback mostly tells the writer that his or her skills are non existent. You can write enough to fill the Library of Congress, but if nobody reads any of the things you write, why were words put to paper?