You've heard that SEO is simple. It's even been called a cheap commodity. If you've been involved with SEO for years, you know that SEO can be ridiculously complicated, (even though Raven tries to make it easy).
There are hundreds of combinations of variables in the signals that search engines, like Google, consider.
In an industry that never seems to agree, I'm going to find the midpoint and state, SEO is both easy and hard.