One way to look at it is emphasizing the power of link rot. These links typically cost dozens or hundreds of dollars to put in a single link in the MDH, up to the max of $37k; the linkers were motivated and knew that much of the value was in having a valid link to click on. But barely a decade on, even this isn't enough for a majority of links to still work. Interests are too ephemeral, people move on too much, control of domains and hosting are too hard to maintain, even when you are paying thousands of dollars. Linkrot is inevitable.