I am always happy for people who can work without meds, but extracting out from that to assume that every physical/chemical balance can just be cured by addressing some reversible root cause isn't really sound logic. There are lots of situations where our bodies don't produce enough of a chemical and there isn't really a solution for that other than to introduce more of that chemical.
I also feel like:
> We know that ADHD is primarily caused by low dopamine
is a bit of an oversimplification. ADHD is not always caused by low dopamine/norepinephrine/etc production, it's often in part caused by faster than normal reuptake of those chemicals. But when arguing that ADHD is entirely caused by environmental deficiencies, "you're not producing enough dopamine" sounds better than "your brain is absorbing dopamine too quickly so it's not signaling as effectively as it should even when it's released in the same amounts as other people."
And again, this is complicated and different people's brains work differently, medication isn't right for everyone. That's why doctors should be involved. But what's going on is a lot more complicated than "something in the environment is making you depressed so you don't release dopamine" or "you don't have enough of X vitamin so your body can't produce the chemicals it needs"; it's more accurate to say that ADHD is often caused by differences in how actual neurons and synapses interact.
If reabsorption is happening prematurely, it's not necessarily that less dopamine/norepinephrine is being produced, it's that the chemicals being produced aren't as able to be used to do the things they're supposed to do.
And that more complicated explanation ends up being a lot more useful to describe some of the less well-known symptoms of ADHD that sometimes pop up for some people; symptoms like hyperfocusing, poor interoception. It paints a more complicated, multi-faceted picture of how the body can find itself unable to stop focusing on things when neurotransmitters do manage to finally bond, or why certain bodily signals just don't seem to reach the brain reliably. I am not a doctor, but I think it's a lot easier to understand what ADHD does when you look at through the lens of a physical difference in the brain that has knock-on effects on how the brain continues to develop as it learns to rely on other signals and coping mechanisms and strengthen those pathways.
TLDR I kind of disagree with the explanation of people with ADHD as if they're dopamine-deficient, I think where modern research is leaning is that they (often, everyone is unique) have brains that aren't able to make use of the dopamine (and other chemicals, not everything in the world is dopamine) that is produced.