Your second paragraph is incorrect. Withdrawal is not an orderly transition to a previous physical state, it's the presence of previously unseen symptoms, typically due to biochemical adaptations to the presence of the foreign substance.

For example, if you drink a lot, some normal neural pathways are repressed by the regular presence of alcohol and your body compensates by increasing the affected neurotransmitters (GABA in this case). As a result, when you stop drinking, you have a corresponding oversupply of GABA, causing the physical symptoms of Delirium Tremens.

I was on Lexapro for 3 years. When I tapered off according to the standard protocol (already in place to avoid withdrawal issues), I experienced debilitating vertigo symptoms and had to change my process from a 2 week reduction to a 3 month process. It was intense.