Content is essential, but SEO places that content in front of the user your business always hoped would read it. A solid SEO plan won't just rank you for a handful of terms, it should shift the whole identity of your site. Enabling it to rank for tens or hundreds of market-related search terms.
Rank for a handful of terms and you will get a handful of results, change the way search engines classify your website and your ranking potential is unlimited.
But here is the part of SEO that is so powerful that no one talks about it. Trust. Of all the channels that drive traffic to a website, the trust factors are rarely better in any other traffic source. Keeping a user on the site, getting them to engage with more of the site, and leading them to action occurs more often if they find you organically. To know, to like and to trust a company happens in a few clicks when they get to a site and that first click of that process is the Organic Search result.