Eric Schwartzman on the Myth of Organic SEO and what he learned delving into the realms of black hat and negative SEO:

Google is doing updates daily to its [search] algorithm. We’re just hearing about the ones that have PR value.

The reason that they want to keep us in line [with their ideal SEO best practices] is because they want it to be less expensive to have to process what’s going on on the internet to decide what to index and what to serve.

This is about more than [just] SEO.