Ghosh: Around 2005, people used to do this thing called “Google bombing,” where they would put links. One of the responses from Google was to require that all websites put a “nofollow” tag on links that are not created by the website itself.
So if you had a link that was posted in the comments, or posted by a user — which includes things like Wikipedia or all social media — which has not been created by the website [then you had to add a "nofollow" tag]. So the authority model — where, when a website links to something else, it gives its authority to that thing — that model breaks down because the website is no longer controlling who puts that link on its pages. So for all links of those types, they were forced to add this nofollow tag so that [the links] could be ignored for the purpose of computing authority. What that means, though, is that, while it was breaking the earlier authority model of Google, [Google] did not change their authority model in response to the way the web was changing.
And the web changed so that the authority model of the new web is that people are the sources of authority. This was always really the authority model, but 10 or 15 years ago, a website and a person were pretty much the same thing.
Wired.com: A website was a useful proxy for a person or a collection of people (an institution, say).
Ghosh: Yes. And that changed when you had different people posting on the same website, or the same people posting on different websites — that proxy didn’t work anymore. But Google didn’t change their authority model.
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