Because EVEN if, EVEN if those tests would show to be conclusive, which they show as much to be as that vaccines cause autism, what are you going to do with that info? You're going to take away every vector of stress and anxiety separately like that? You're going to limit and avoid your whole life around the fact that every.little.stupid.thing makes you stress? No, the entire problem is how stress in its entirety has an effect on your stuttering, and you want to disconnect those two from each other. It's combatting cause vs. symptom.