It's always a good idea to put some articles on other sites for reference back to you as well as links to your site.
RitaAnn~

I don't know if it's a absolute necessity to write content to other sites or bookmarking your content. but I do know that it helps with ranking your site.

If you bookmark your content, more people are gonna see your stuff, since its seen in multiple sources, giving you increased traffic

Writing for article sites such as streetarticles or ezine etc also gives you backlinks and increases your traffic if you target the right landing page and write quality material.

Remember articles sites carry a pagerank... most of the popular ones have high pageranks... so when google go through those articles that you wrote to in article sites with a higher pagerank than yours they index your site faster.