Short answer: yes, yes you do.

Why? Picture all of your website visitors as a massive pie. For the average website, 50% of that pie will come from search engines like Google.

Search engines are a discovery tool, meaning that many of these website visitors are discovering your website for the first time. As more and more people discover your website from search engines, you’ll see each other traffic channel (email, social media, etc.) increase as well. In other words, as this part of your pie gets bigger, the rest of your pie will get bigger as well.