Most noots don't necessarily deplete neurotransmitters, but they definitely change the uptake cycle. If you supplement choline alongside most nootropics, then your brain has the catalyst necessary to reuse neurotransmitters effectively. That's why choline by itself can have a positive nootropic effect on deficient diets, and that's why you'll see it in almost every stack. It's very important to a balanced stack.
Some racetams are known to be ampakines , which are covered by this article. Noopept also appears to be an ampakine.
I don't necessarily buy into their caveats, because they're assuming a runaway train of plasticity that starts overriding the foundational patterns our brain has learned, like colors, tastes, emotions, and so on. They're looking at the brain as a monolithic system, which it is not. They're treating it as a black box, without taking into account the metabolic pathways and so on that we do already know.