It's not just the spiritual side either. Traditional knowledge is also about stuff like exactly how much to use, how to prepare it, what to use it with (and not to use it with), what time of day, beneficial activities before and after, and so on. The human body is a complex system where all of these things cause complex interactions that can influence efficacy. Traditional medicinal use is full of these kinds of 'full package' treatments, a lot of which is lost when you just bottle some ingredient.