The devil in the details is how you pull something like this off. At the end of the day is boils down to how do you enforce that your team does the right thing. You can have a single person that enforces standards with an iron fist, but this doesn't scale. You can teach everyone how this should work, but you're going to experience drift over time as people come and go. Or you can enforce it using technology and automation.
In the cases of the first choice, its going to restrict how big your team can get and will end up eating all of the time of your one person.
In the case of the second choice, a combination of the tragedy of the commons and regression to mean will degrade the system to spaghetti code.
For the third scenario language choice matters here a lot. In Java with multi maven modules you can setup maven to forbid imports of specific module types allowing you to make modules as private/public. In Python you can't do any of this.
It’s also ready sold OTC.
Instead people just sit around and do meta studies on meta studies on correlation and publishing whatever statistical anomalies they can find.
Choline a key component in Acetylcholine is the primary neurotransmitter used in your hippocampus. Its an excitatory neurotransmitter meaning it turns neurons on. The hippocampus is a massive parallel feedback circuit that when over stimulated can and will begin to seize. In fact many people who suffer from seizures have over active hippocampal circuitry. Simply "flooding" the brain with more choline could have very very bad effects.
Likewise, taking choline might not work as the brain actively controls and regulates the contents of the cerebral spinal fluid. Unlike the rest of your body, the capillaries in the brain are not leaky, but instead are enshrouded in the blood-brain barrier and there are active transport proteins for anything that isn't lipid soluble.
Choline is actively transported into the brain and the brain has additional internal mechanisms to regulate the levels of choline.
Lastly, neurotransmitters aren't just floating around in the soup of your brain. They are released by specific neurons which are integrated into specific circuits. Parkinson's disease is a perfect example here. There is tiny region of the brain involved in regulating voluntary movements that is rich in dopamine neurons. For Parkinson's these neurons die off while the rest of the brain remains relatively strong. Simply putting dopamine into the brain doesn't fix the issue you need to up the dopamine released by these specific neurons.
The treatment here is l-dopa which is a precursor to dopamine which does this, but once those neurons are gone they're gone and there is little we can do to stop the disease.
So if this works for l-dopa why won't it work for choline? My guess is because of the tight regulation the brain has around choline levels as its needed to prevent the hippocampus from seizing up.