hackmum I find your posts rather strange tbh. Do you have a medical background?
I really don't understand what you are trying to say. That "mental illness" doesn't exist? Or that medicating it isn't helpful/good/right?
"Yes, SSRIs and ECT do release chemicals into the brain. But it may be a mistake to assume that the depression is caused by a lack of chemicals in the first place. To take an analogy: if you have a headache, paracetamol will make you feel better. But the headache wasn't caused by a lack of paracetamol.
Let's put it another way. One of the things we know now about the way the brain works is that it responds to the environment. So if you are unhappy, that may cause the serotonin in your brain to drop. Replacing that serotonin may make you feel better, but it isn't addressing the cause of the depression."
A lot of common medical conditions are of unknown cause. Over 90% of high blood pressure is idiopathic (cause unknown). To use your analogy, if the doctor gives you a diuretic for your blood pressure, it works by acting on e.g. the kidney to absorb less salt and water. Result is your blood pressure drops. But for the vast vast majority of people there is nothing wrong with their kidneys. The medicine is just a tool that doctors use to bring the body back to its normal, 'safe' state. Yes, perhaps if some of these people ate a perfect diet and went running every day their blood pressure might drop a bit. But for some it wouldn't. And if people stayed unmedicated and were unlucky enough to be in the group whose blood pressure stayed high, then they may get cardiovascular disease. They may have a heart attack or stroke.
The exact same applies to depression/other mental illnesses. Yes, we may not know the exact cause of the neurotransmitter depletion (although science does have a better idea than I think you think it does), but we know that giving antidepressants can increase levels again and ultimately upregulate receptors that have become downregulated. We could alternatively tell these patients to just relax/take up exercise/have counselling/quit their job/whatever, and some may get better on their own. Some won't, and may commit suicide. That's why psychotropic medications cannot be disregarded. In many cases it can save lives, exactly the same as anti-hypertensives do.