The author was the interviewer, and the comment came from a candidate that wanted to research his interviewer as preparation for the interview.
The reasoning why he thinks one should have a personal website follows in the paragraphs "Practice" and "Learning".
That's weird as well, I would never research the interviewer (as well as I never got to know the interviewer prior the interview) but instead abouth the company, business, technologies and things like that.
About practice and learning you don't have to have a website, there are many ways to keep your memories and skills up to date.