How often are you reading a not-that-old article online and the author makes some external reference that has since vanished?
Sometimes, the web is forever; the web will archive it all for the good of humankind! But just as often pieces vanish, as above.
From that same article:
Online has no boundaries and online can be fiddled with indefinitely. We trade solidity for instantaneous and boundless distribution. It’s a pretty good trade.
Despite the irony, I don't disagree.