Would anyone believe a doctor who claims that he or she is able to treat all medical problems? We would all think that the doctor is out of touch with reality.
The issue is that many church leaders are selling the same myth (It is a one stop shop). There is occasional referrals to other church leaders or other Christian organization. If you are unlucky, it ends with the pastor who decides to victim blame.
It is not that doctors can always prescribe little white pills. It is that they can escalate the issue if their experiments fail. Or at least Google it.
I am not saying that doctors are necessarily better in fixing minds than churches. It is just that if you only have a hammer, every problem looks like a nail.