This is a tragic story, but from what I see here the bf angle seems mainly to be the 'spin' the DM has chosen.
She seems to have switched to mix feeding before the final crisis. I am sure that the stress and unhappiness caused by bf problems did not help at all, and yes it sounds as if she could have been better supported here, but crikey, this was a catastrophic failure of the service to recognise a patient in complete crisis, and the DM focus on bf undermines that!
Would she have been absolutely fine if BF had gone well? I doubt it.
Would her depression have been exacerbated in a similar way if midwives and HVs had intervened to stop her bfing, telling her that she shouldn't put herself under pressure/baby health comes first/bf not that important really, etc. etc.? Quite possibly.
The latter happened to a friend of mine. Found BF very difficult, ultimately gave up. The response of the health professionals seems to have been the opposite of this poor lady - they immediately started to tell her she shouldn't worry about it, give a bottle, don't put herself under pressure. My friend says this did the opposite of helping her - she SO wanted to bf that she felt unsupported and undermined and made to feel like a bad mother who was happy to see her baby not thrive so that she could get to bf!
It's not so simple. And I think focusing on one aspect, like the DM story, is very unhelpful.
Poor woman.