I think the article is only true for situational depression. When people are depressed for no reason and for a long period of time, then the depression is not advantageous to them. I agree with some others in this thread that it's a genetic weakness. For this group of people, researchers discovered that the success rate of treatment is low. Only 1/3 of adults show a postive response to drugs. (Some or all of their symptoms are controlled). The most effective treatment for clinical depression is a combination of ONGOING therapy and medication. Even with combined treatment, the success rate of recovery is still too low.
In my opinion, medication should NEVER be used in a child. There is not enough conclusive evidence that prove that the benefits outweigh the risks. We don't even know all the risks involved. Some articles say that long term use of SSRIs (a class of antidepressants) affect the development of a child's brain and that this effect is permanent. That's scary! Don't use medication in young children or teens.