I don't give enough credit to Dr. Mew in my posts. I wanted to clarify my extreme and pronounced appreciation for their immensely relevant research in the critically important and vastly underrecognized realm of facial development. Without them, I wouldn't know anything, only suspect a few things and never really know.
To be quite explanatory, I wanted to show this graph:

These men are innovators, dedicated to helping the masses. The are innovating in the health and airway space like none before. As any explorer, they blazingly set a trail. Like any great expeditioners, they have put their lives at stake to trek in the unknown. You can witness to the level of care and concern Dr. Mike Mew has put his family through. His passion is from his heart and he has risked it all. Inevitably, the concepts that he is providing hold true. The nuances of these concepts are being worked out and that is what's happening.
As it pertains to pressure, I tend to favor appliances. Pressure applied by the tongue is potentially useful in cases, but it is highly variable, with outcomes such as uneven jaw disarticulation, pressure upwards, and not just lateral (airway no-no), and even growth of the tongue itself. The entire concept is to make the tongue fit, so if it grows, then you're basically chasing your tail, if that makes sense? Additionally, the tongue would apply downward pressure and this can create a pronounced bowing (curve of spee) which many have reported. Newton's 3rd law is always in effect: every action has an equal & opposite reaction. I have been disheartened by the lack of a disclaimer aimed at protecting the viewers: https://www.youtube.com/watch?v=5vuGLsBzz_0 Here, the disclaimer is primarily aimed at protecting the establishment. This was especially disheartening when I'd discovered that Dr. John Mew has been early-on aware of the implications... such as curve of spee. I feel it is reckless to put a disclaimer out and not respond for follow-up to reported concerns. This headstrong attribute is an embodied characteristic for those who are true innovators. Just know what you're getting.
There are some others who follow Dr. Mew, inside the profession and without. These early adopters are allowed to be more nuanced in their approach, with less chance for results including the following:
Maxilla inadvertently retruding
Lower jaw being pushed back
Newly developed facial asymmetries
Bite problems, including clicking/popping/jaw isssues/headache...
This last one is one of primary concern for me individually, and I wish that there was a disclaimer. Every time someone hobbles into this space who has been hurt, I just feel sad. The Admins on this site allow for various viewpoints. I would not have stayed here otherwise. We are all just seeking the best way forward. Although conceptually we are subjects of overarching development principles, we are all unique in our facial structures. Individually, we have different paths forward. This can be overwhelmingly confusing. Marketers on every side are pushing products at us. Sometimes even a blind squirrel gets a nut every now and again. Many orthodontists just honestly don't really know what they are doing. And so I've witness this site become sort of a gut check on proposed treatment plans. If you go to 10 different orthodontists, you will get 10 different treatment options, with 10 different resulting outcomes. This is true even for a mild case of crowding during phase 1. Imagine the confusing and bewildering navigation through the jungle of orthodontic maneuvering that adults face! Ideally, we would be able to resolve these things naturally when young. That is the concept behind orthotropics. Its founder, Dr. John Mew said that early intervention is key. There is even a specially designed pacifier for this now. For adults, it is often too late. The concepts being applied, though, are from my estimation things to use hand-in-hand with orthodontic treatment. Defining orthodontic treatment as anything unnatural resting against the teeth/drilled into the jaws/bite appliances/headgear. Many makers say they're not orthodontics, but they are by this definition. Orthotropics is not the absense of appliances. Even orthotropics uses appliances, like Bill Hang. He is a friend of the Mews. Dr. Mew uses appliances. It seems that everyone out there has something that's "not traditional braces". Even Dr. Bill Dickerson pooh poohs on braces and uses them. This confusing market differentiation strategy is asinine. The established patterns of behavior will fundamentally determine the long-term treatment outcomes (especially in cases without a retainer). This is not always the case, as sometimes treatment allows for new behavioral patterns to naturally evolve. We see this effect commonly with more severe treatments. Just one such example is the person with a severe tongue tie who receives orthodontic care and it relapses. Another is someone with poor oral habits who receives intense orthodontic treatment and because the oral habits are not resolved, they may relapse. A multi-faceted treatment could be necessary. I see some really perceptive early adopters in this space, and that is heartening. Whether it's the local orthodontist who looks for patients breathing through their mouth, orthodontists who ask the child to lift their tongue, those who utilize sleep study screenings or CBCT, those who look for dark circles under the eyes, pale gum coloration, or a pale or long face, abnormal growth patterns and the like - it matters. Whether it's those who fill the void on airway comprehensive treatments: Vivos and Sue Lee - it matters. There are others, but these 2 have honed in on the whole enchilada. I make no money off of saying any of this. Whether it's me or you, sharing our experiences - it matters.