It's a way of describing "depression" in a way that doesn't feel compatible with blame.
Are you implying that depression or BPD is 'compatibile with blame'? If so, that's absurd.
No one would ever blame you for a [genetic] heart disorder. In the same way, no one would ever blame you for a [genetic] brain disorder. Phrasing it as such removes some of the stigma.
I think that the way to beat the stigma is talk openly about it.
Easier to say than to do. If you're depressed / bipolar / schizophrenic and talk about it openly it can make people very uncomfortable, which can result in their not wanting to be around you, which can result in further isolation for you, which can make your situation worse.