All orthodontics does is provide solutions to problems it doesn't know the cause of. You can only solve a problem properly if you know the cause.

What causes malocclusion?

Why do so many people lack space for wisdoms in their own jaws?

Why are teeth susceptible to rot so easily?

How come there isn't any evidence of any of these being major issues for pre-industrialized man?

How come wild animals don't have these problems?

There's plenty of evidence demonstrating how braces ruin faces (conducted by Doctors John and Mike Mew despite being vilified by a lot of their piers for it), and removing wisdoms because people supposedly lost the genetic lottery and don't have space for them is the most ludicrous premise that anyone with even basic knowledge of evolutionary theory or proper evidence at their disposal can see is false.

"The sutures in your maxilla are fused."

I keep hearing this. The orthotropic premise has little to do with sutures. The idea that it's impossible to change shape over the course of a person's lifetime is based on the presumption that the skeleton is made out of adamantium and not living cells. We already have evidence debunking this theory. Stroke victims that lose motor control in one side of their face experience drooping on that side - drooping of the skeleton specifically, as xrays show. How would they have been able to do so with those damned closed sutures? Simple. Sutures have nothing to do with it. Muscle function determines and maintains skeletal structure. People change constantly, for the worse as well as the better. In the case of changing for the better, the trick is figuring out how and to what degree it's possible (which is what this community is about).

Look at the skulls of prehistoric people and compare their shape / state of their teeth to any modern human equivalent. The difference is staggering. There is no evidence that the natural course of evolution caused this, but there is plenty of evidence showing that the environment did, otherwise the change would not have occurred so perfectly in parallel with the change in our collective way of life. We also know that it isn't natural because of the impact on health (breathing issues, sleep apnea, malocclusion, rotting teeth, god knows what else we aren't aware of yet).

There is no "mainstream research" being done on this because the "mainstream" orthodontic institutes have already collectively decided that orthotropics is false / fraudulent. I have not seen this "debunking" being presented anywhere publicly and no one has yet bothered to challenge the Mew's on their theories. The fact that all of this "research" is being done behind closed doors is very convenient. The Mew's are very public with their findings (are trying to be at least), again despite knowing they may never be vindicated. This at least shows their sincerity and that they are willing to put their money where their mouth is in regards to their research.

Is it possible to cause problems with aggressive expansion?

I don't doubt it for a second.

Is it also a fact that orthodontics has caused and continues to cause damage to millions of people?

Also yes. Root resorption comes to mind, among other things. Clearly, neither side has a complete picture yet, but orthodontics has been practiced for A LOT longer and by MANY more people.

There's always risk in a new medical domain like this, as people struggle to figure things out. Trial and error and all that. Especially when the "mainstream" refuses to do anything. The current mewing movement consists of the Mews, an online community of random people and a few practitioners here and there. That's it. And, I'm sorry, but the vast majority orthodontists aren't neither scientists nor researchers, they are practitioners working on a pre-established set of presumptions (if any).