To me it's a case of ones responsibilities. You can easily be a technical based SEO and not consider other factors of marketing if you are more entry level and have a good support structure at your organization.
If on the other hand you are managing projects and goals, you need to have a wider set of skills than just knowing how to get indexed. SEO has to fit in with traditional marketing efforts to be fully effective. If you don't have that perspective, it won't be effective.
For people like Justin and Rand, being mostly consultants, they need to have a grasp of wider inbound marketing if they want to do well for higher end clients. You can only go so far by building low level links and optimizing on page factors.