This is exactly what I was thinking as I read the article. I think of it as a sort of mantra that can be applied in a variety of directions, whether you're a startup founder, an early-stage employee, an employee of a larger organization, or just a human being trying to make the most of your time.
i.e., "Am I doing something worthwhile?" -- which could mean different things depending on the context, the goals or principles of the person, or what have you. I guess it depends on how you define "value" :)
I think the question "How do we add value?" is important, but only in the sense that it can help you figure out what are the key activities of the business, that you should be involved in. It can help focus you, basically.