Content is the king, social signals are queens?

Content is the king, social signals are queens? Why is content so important for SEO?

Google Panda helps users by filtering out quality sites, and reducing the amount of low quality content such as duplicate content.

Quality content encourages users to stay on, and read more of a site. Through click through rates and the number of social signal shares, quality sites gain more visibility with search engines.

Branding tells a story, and stories rely on content. An outstanding site will become the authority in a particular niche, and an authority site creates a branding effect. Statistics show that 50% of users are more likely to click on a search query, if the brand appears a couple of times in the result page.