This makes sense because one way to think about practice is as an experiment. Using the mind of inquiry and study of the teachings, we develop an idea about how life and the greater universe really are. Then, we sit and we go about our daily lives, and we see whether our actual experience is in accord with our understanding. This is radically different from most religious traditions which are based on faith.
Don't get me wrong. There's nothing wrong with faith; it's simply that Zen doesn't rely on it. Zen relies on actual experience and the study of the true self within the mundane world of body/heart/mind. And zazen, the practice of Zen sitting "meditation," is a way in which things are simplified, stopping activity so that the study of experience is nearly unavoidable.
Sitting down or not, it seems the world is catching up to the Buddha!