The reason comments/shares/engagement are important is because the way people find news is shifting to social. SEO is still important because news on TV and Radio (and read over the shoulder of the guy in the subway) necessitates searching for the article when you get yourself online.

Disclaimer: I'm root@buzzfeed.com - Jonah Peretti (Huffpo's technical co-founder) is our CEO

When you don't notice that Jean-Louis Gassée is a co-author