Startups typically have a new solution to solve a customer problem. Successful startups benefit from understanding these problems. SEO is a great way to get a startup going to reach these people and turn them into customers. Getting a solid SEO foundation and strategy is a great opportunity because you're starting fresh. Build things out the right way at the start can make all the difference. The number of startups that build their first success wave on SEO is endless. Once it's proven with the "free" traffic investors will poor rocket fuel on it to bring in the other channels, but only if it's proven that there actually are customers searching for the problem and the startup business reaches them through SEO.