I agree with you, @Paintedseashell. I have had depression since my mid teens, due to bullying at school that was never tackled - I was having suicidal thoughts by the age of 14. I wasn't formally diagnosed until I was in my 40s, but the psychiatrist and psychotherapist I talked to about my childhood and my feelings during that time were very clear that what I was feeling was depression - being suicidal at 14 is not normal, they said.
I was diagnosed with PND after my first child, and had it after the second and third too, but now I wonder whether this was the clinical depression, exacerbated by a bit of PND.
I've been on antidepressants for years, and each time I've tried to come off, I have slid back down into bad depression again. I've also had group therapy and individual Congnitive Behavioural Therapy, which have helped, and have given me tools to cope with days when the depression is worse.
I think I will never be free of this - I think there will always be a certain amount of depression in my life. I actually had a medication review with my GP this morning, and he suggested I might like to try reducing one or both of my antidepressants (my psychiatrist put me on a combination of mirtazipine and fluoxetine), but I am not going to do that - I don't want to risk going down hill again - at the moment my mood is low-ish, but stable, and I can live with that - and I'm not willing to meddle with something that is working to some extent, even if it's not making life perfect.
But I do think that, for some people, depression is an illness that they can get over completely - with the right help - and that is great (though I am a bit envious). I don't think it means that they are stronger than people for whom depression is a life long companion - I suspect it means the roots of their depression are different, and were more easily tackled. Maybe their depression was situational, and when the situation changed for the better, so did their mental health.
It is a very complex subject - I think depression has physical and psychological roots, and the effectiveness of treatment depends, in part, at least, on the root causes. I do believe that some depression is caused when the brain fails to produce particular neurotransmitters, and if that's the case, they need replacing artificially, via antidepressants.
If someone's pancreas doesn't produce insulin, no-one judges them for needing insulin for the rest of their life - I think depression should be the same - if I need antidepressants, to make sure I have the neurotransmitters I need, and if that is not going to resolve (ie. my body is never going to start producing them again, of its own accord), then I shouldn't be judged for being on medication the rest of my life.