By sharing a blog post or an article with great quality content, your post will go more viral and also creates interaction with users which increases brand awareness.
Social bookmarking is a technique to get huge traffic along with branding and promotion, good number of back links (link building).
By submitting on high PR bookmarking sites, your blog post will be indexed more quickly and also helps to generate new relevant traffic. It also improves domain authority, reduces bounce rate. Each bookmark provides a backlinks to your website.
Social sharing helps to make your site more famous everywhere on the web. As there are so many SEO techniques, but social bookmarking is very effective.