Attribution doesn't necessarily need to be a name or contact information. It just has to help end users identify the provenance of a work of intellectual property. A URL does that. Many end users are already including URLs in their code to indicate where they found a snippet - compliance with the new terms is already somewhat socialized. That's a big reason we chose these terms. We spoke at length with the Open Source Initiative about using a URL as attribution, and they agreed it works in our case.