That opinion is widely held by mental health professionals. Here's an excerpt from an article that reports that one in five American adults is taking a psychiatric drug, which seems excessive to me.

"I would say at least half the folks who are being treated with antidepressants aren't benefiting from the active pharmacological effects of the drugs themselves but from a placebo effect," says Steven Hollon, PhD, a psychology professor at Vanderbilt University who has conducted extensive research on the effectiveness of antidepressants. "If people knew more, I think they would be a little less likely to go down the medication path than the psychosocial treatment path."
The use of psychotropic drugs by adult Americans increased 22 percent from 2001 to 2010, with one in five adults now taking at least one psychotropic medication, according to industry data. In 2010, Americans spent more than $16 billion on antipsychotics, $11 billion on antidepressants and $7 billion for drugs to treat attention-deficit hyperactivity disorder (ADHD). The rapid growth of all three classes of drugs has alarmed some mental health professionals, who are concerned about the use of powerful antipsychotic drugs by elderly nursing home residents and the prescription of stimulants to children who may have been misdiagnosed with ADHD. from:Inappropriate prescribing