Even if an antidepressant would not work better than a placebo in treating depression, I experienced a case where its usage could be worthwile: if the side effects are beneficial. Someone I knew needed better sleep and more appetite and they got an antidepressant with two side effects: weight gain and sleepiness, to take just before going to bed.

So they got better because of placebo effects and better sleep and weight gain.

That's fine with me.