I can understand what you mean to say, I think. For example, cognitive behavioral therapy aims to change the way in which people suffering from depression think in order to cure them. It can be quite effective. However, in many cases with major depression different therapies, trauma treatment or medication is also required. In the worst cases, someone might need electroshocks.

I think the issue is that people with depression and people with eating disorders often get blamed for it and they often blame themselves. They are legitimately ill and it is not their fault, just like having any other condition is not your fault. However, due to society's message of 'just say no' to depressive thoughts or food, they might keep on blaming themselves and feel like they are a failure and should just try harder. This can make them just fall deeper in the pit they are in, instead of getting the treatment they need.

I think the last part is not what you meant, but it sounded a bit that way.