Social media builds trust with people who already know you, but SEO captures strangers searching Google for what you sell. Most businesses need both to reach the full pool of potential customers.
Okay, so why should you do SEO if you're really only using social media to connect with clients? The reason you want to do both social media and SEO is because some of your clients are going to find you, watch you, and enjoy you on your social channels. And that can be really great for lead gen, but many, many people use Google to find the services that they need help with. They use it like it's the Yellow Pages, or they use it like a dictionary. So when somebody is looking for you and they follow you on social media, they know you, like you, trust you. It's an easy lead. But what you want to be found by for your business is strangers. You want strangers that need your services, strangers that are interested in your products, and strangers that want to work with someone like you but have never heard from you. And a lot of people don't do social media. So if you want to find all the leads that are out there that need your services, you really do have to do both social media and SEO.
