Unless paired with something, antidepressants won't fix the base problem.
The base problem is a chemical imbalance in the brain that causes it to be inefficient at producing and/or absorbing the chemicals that allows an ordinary person to feel happy.
A lifestyle change can improve this quite a bit and for some it can help enough that antidepressants aren't necessary, however
1) Depression has no external cause, only external aggravators. (There is no cure for depression)
2) People who get off of Antidepressants might eventually need to go back on them for a bit.
3) It can take a long time before a proper combination of antidepressants and therapy become useful/helpful. There is no magical key to depression wellness.
Or rather...Your idea is for a subset of people who suffer from depression.
Most people would be quite happy if antidepressants, a bit of therapy, a decent job, and a clean room would cure them in a matter of months. In fact, can I take those antidepressants?
----
HOWEVER and I am sad I left this to an edit...
Yes, it is improper unless someone needs no lifestyle changes or extensive therapy (it does happen, it isn't that uncommon) that someone can just stick to antidepressants.
In fact the usual reason why someone is allowed to take antidepressants without going to a Therapist? Because depression often prevents people from aiding their depression. Antidepressants indeed can be a cure on its own.
Well... Except that there is no cure for depression.
---
To put Depression in context.
The greatest day of your life, would probably make you extremely depressed. The best thing about depression is that it takes a lot of hard and consistent work because everything good that happens to you, is equally depressing because of the way your body handles it.