The answer is both 'yes' and 'no'.
Yes if your on-site optimization efforts are geared towards complementing a solid, long-term back link strategy and
no if dependent exclusively on back links to obtain high search position.
We once had two clients with opposing views on the importance of both linking and content creation. Client #1 was so afraid of being back linked to the ever dreaded 'link farm' and thus receiving a search engine ban that they refused all back link efforts.
...