It also shows how few people had access to the Internet in 1995. Over the course of 4.5 months, the author received 13,500 personal letters via snail mail. In the same period his website received only 50,000 pageviews, but he thought of that as a very high number.
Fast forward to 2010: any moderately successful blog will receive 50,000 pageviews a day, but its authors will probably never receive 13,500 personal letters via snail mail.