In the earlier days having a blog was an instant hit. People who embraced writing web logs from the beginning, did get a lot of extra exposure. Now the mass is jumping on a train which already left the station some time ago.
The success of the first blogs explained
The first blogs on the web were non commercial and that was the first ingredient for their success. Second, web logs are quality content and can be made really easy. As we all know search engines like Google really love good content. The first blogs could be on top of search results in mayor search engines like Google in a matter of days, where other (big) websites struggled to get the same result in years. This could happen because web logs contain loads of text which is related to quality content. Other traditional websites tweaked their sites with tricks that did not compete with the awesome power of blogs: honest quality content.
These days loads of people have their own blog and I must say 90% is not even worth reading. Because the amount of people having a blog is exploding, search engines which finally were able to find some good content related websites, now have to struggle with the millions of blogs with absolutely no good content at all. Many blogs are not updated on a regular basis, they are often made to sell products or used for marketing the thousands