I have not problem with the concepts of Natural Horsemanship - it’s the practice/teaching of a particular person that aren’t good.
Case in point, I started working with a couple and their pleasure horses last fall. The husband showed me what he was doing and I was like yeayea all good - the horses didn’t seem happy but I had no need for that so just didn’t even address it on first visit. He was doing something in the round pen with a long crop to get the horse to move in a certain way. I merely told him, with 18 year olds, sometimes that stuff is just a bit lost on them. We continued to talk about how it isn’t bad per se but may be a bit like teaching a horse a new language.
While I was riding them, the one horse would not stand at the mounting block. I don’t know his history, other than he was a lesson horse. But he seemed nervous/worried about mounting. So I used a classic Natural Horsemanship move - pressure and release - step on the bottom step, back off, on and off several times until he settles (with good boys and breaks). Then, gathering the reins was a trigger, and putting your foot in the stirrup. The couple was away for a bit, then winter made riding less than ideal so we started up again a month ago and the couple was very engaged. The horse now pretty much stands at the mounting block and they told me he previously would not only not stand but would rush off once someone was on/half on. Now, we are at the point where we can walk up to the top step, pick up/drop reins maybe 3 times, foot in stirrup and out maybe twice, then get on and he’s good.
That’s all Natural Horsemanship I learned.
NOW - counter that with the stick thing. We were working in the roundpen a bit over a month ago (when we first started back up) and they did mention he always seemed tense in the roundpen except when I brought him in. Initially, I had no answer. On another subject, I asked for the long stick to show them something. Horse was already in the roundpen calmly hanging out. As SOON as I walked in with the stick, he just lost his brain - he would run about a quarter of the way around, outside turn, run back a quarter, outside turn, repeat until stick was removed from the roundpen and he took a breath.
We all looked at each other and light bulbs went off - they had always walked into the roundpen with the stick so never noticed the difference. Other horse did not have that reaction (old ranch horse) so it wasn’t the couple, it was something in that horse’s past.
All that to illustrate - it isn’t the type of training, it is the practice/teaching. This couple were fairly novice horse people. They had leased before but not really had gotten a lot of instruction, then bought these horses and kept them at home and no one that taught them the natural horsemanship skills said anything about not all horses needed X, Y, Z; or possible issues.
Anyone worth their salt needs to explain these things - they have two horses with two different personalities and we spend a lot of time discussing how the horses are ridden differently because of that. I see the same issues no matter what methods a trainer uses - if the trainer is unwilling to adjust, then some horses will suffer.