If you read what Peat wrote about chemical withdrawal and caffeine, you might see things differently. He described a withdrawal as a psychological effect produced in pursuit of a physical stimulus that the organism's biology had adapted to, seeking to return to that state of stability to which it had become accustomed. Thus, even a lack of beneficial substances like coffee, food, vitamins, and even bright light could cause withdrawal symptoms.
Coffee is of course more stimulating that most foods and vitamins, but it is also chemically very similar in structure to thyroid hormone, which will increase mood through dopamine stimulation, but also by its own merits. I don't believe that biochemistry is as simple as a few neurosteroids, the best approach is to promote generative energy through thyroid, nutrients, carbs, caffeine, etc in order to maintain dopamine strength which anagonizes serotonin spikes.
Coffee has been shown to down regulate serotonin production as well as increase dopamine receptors, as well. I think the tiredness and brain fog I experience when I don't have it is withdrawal from the stimulation, but not a sign that it is downregulating dopamine, in fact it is likely the opposite.