That is the moment you realize the internet is huge. That someone could make a living out of a weblog yelling at clouds and you never heard about it despite being online almost every day during the same period.
It's one of the early waves of blogs, popular on the early internet. I don't think it was really "relevant"/popular in the last 5-10 years, but I might be wrong.
First, I was pointing out the shortsightedness of the comment to which I had replied. However, your question is answered in the article.
The author's age is related to how long Kokkte has existed as a blog, which is longer than those who are 30 today have been browsing the web. From the actual article, "I’ve been writing kottke.org for 25 years". This means that people who are over 30 today were the initial boosters for kottke. Kokkte is a person's blogsite, not something targeted to people under 30.
As the article says, kokkte.org is older than google. The author didn't start blogging when he was 5.
There is also a pertinent point on wikipedia about Jason Kokkte. "In 2005 Kottke was able to quit his day job to focus on blogging full-time." [1] He wasn't supported by people who were at most 12 years old.
