Ambrey - I see what you are saying. A conflict of interests so to speak. Yeah, I have seen that before. I have retrained a lot of horses so I am used to walking up to a horse and asking the horse how it was trained and going from there. Many trainers that have worked in one discipline for a long time, whether that be hunter, dressage, western, or something else, will be frustrated at working with something that is outside what they have been doing for the last 20+ years. I can see where that can be a problem as well.
Similarly, a friend took a well broke older horse to a Parelli clinic just to see if it would ‘help increase the bond’. The horse looked at her like she had suddenly grown a second head. She knew how to back up with command A, when being given command B, she just got confused. There was no point in putting any other training into an already trained horse. Just illustrating that it works both ways.
BaroquePony - The traditional method of walking with the horse next to you, opposed to behind you is to prevent getting run over by a spooking horse. The concept behind a horse walking behind you is to teach the horse that you are the lead horse. Ideally the horse should be paying full attention to you and not spooking at anything. Natural Horsemanship uses a lot of herd mentality. While a horse may jump at something,they should look to you immediately for guidance and calm down because you are calm.
I have not had any horse run over me whether they walk behind or next to me. I have had less instances of spooking and running when horses walk behind me - but I have worked with less horses that were trained with Natural Horsemanship techniques, so the data is somewhat skewed.