I believe your right. But when ever I try to relax my diaphragm in situations I have a built in "phobia" about like when saying my name I still get blocked...I learned that on speech class years ago but it never really worked 100% in situations that I get blocked in for some reason. If there was a technique or medication even that relaxes you to the point of not getting a ptsd knee jerk type of block I believe alot of people wouldn't stutter..but yes I do believe most of it is engrained in our subconscious and we need to like you said try to convince our brains we don't stutter it that actually is possible.