It's an interesting idea: though, a couple things:

I think depression is overdiagnosed; you do not need meds to get through the grieving process, or to cope with a new job or school. There's definitely a confusion between situational and clinical depression.

Where's the line between those two, though? People have been saying my depression is situational for years: first it was hormones, then all the school-switching, then "emotional abuse", then an "adjustment disorder". It's been almost half my life with a melancholic baseline and being easily sent into phases of being utterly miserable. It gets worse with age: is it dysthymia or do I just lead a depressing life?