You seem to be getting advice from 2 very different paradigms. Let me try to clarify things so that hopefully the useful advice you are receiving can be applied properly.
Some folks are talking about the need to focus on content, others are talking about building links. You need both.
SEO isn’t building backlinks, though it seems many folks think that is exactly what it is. They are wrong. SEO is something we do to content or include as part of the content we create. It is simply including your targeted keyword within key elements of your web documents. There are many other aspects of SEO, that deal with strategies and structuring of your link architecture.
Promotional activities involve creating content and distributing that content at various strategic locations on the web. Ideally, that content should be optimized for search engines (SEO). Link building is a promotional activity that may, or may not, include SEO.
Link building can be divided into two types, meritorious link building, and webspam. Some of the advice you receive may come from folks who are not aware of the difference in these 2 types of backlinks. So treat all advice with caution.
Meritorious link building adds value to the web, tends to accumulate value over time and is welcomed by search engines. Webspam pollutes the world wide web, is steadily purged and is continuously devalued by search engines, becoming worthless over time.
All meritorious link building is based on valuable content being added to the web. Placing that content in strategic locations, and including keywords in key elements of that content is precisely what SEO is about.