because over time, people lose interest in their websites or they don't have the money to continue them and they die off. The links then go to some unsavory place and I try to clean up the links I have by visiting them.
I checked Opa City this morning, which is a Urban Exploration website, and it is active. As I was going through some of the first page... Man! We used to have a lot of mental hospitals in this country!
I guess most of the people released by changes in laws about involuntary psychiatric committment now run the TSA.