More harm than good? "Absolutely not" with a footnote. Antidepressants aren't 100% effective. In capable prescribing hands, they completely eliminate depressive symptoms about half the time and substantially reduce sad moods about another 20% of the time. On rare occasions someone winds up more depressed on a certain medication, so good prescribing means following people closely and adjusting medications as needed. But many more people benefit than have no response.
Sometimes folks who are especially severely depressed ruminate about suicide constantly but are too exhausted from their depression to act on that impulse. Antidepressants often improve energy before they help mood, so it's well known that someone who's suicidal needs to be in a controlled setting until their moods improve, which takes about 1-2 weeks. Otherwise they may finally have the energy they need to kill themselves.