To last a long time, you need a lot of people hosting copies. Think about PDFs -- it's easy to host a local copy of a PDF, so popular PDFs tend to be widely av

To last a long time, you need a lot of people hosting copies. Think about PDFs -- it's easy to host a local copy of a PDF, so popular PDFs tend to be widely available. But a site hosting a local copy of every webpage it links to would feel weird.