Actually the report says there can be advantages in thinking of depression as an illness and some people find medication helpful. Depression of course can be a normal experience and there can be benefits for some people of 'normalising' depression. The report also makes clear that depression can be debilitating and associated with psychosis at the other end of the spectrum. A strength of the report is that it provides personalistic explanations of depression, taking a holistic perspective rather than narrowly focusing on the brain. I don't think the report is misleading or undermines depression as an illness. It is a helpful, balanced report written in everyday language.
The argument on twitter about whether depression is an illness deflects from taking on board a key message of the report that depression is not a brain abnormality. I wish these debates would become less polarised and focus on the fact that depression is not the result of a brain disease. The symptoms and signs of depressive illness, although enabled by the brain, are not merely epiphenomena of a causal brain process. Depression needs to be understood in interpersonal context. Maybe that's why some people feel so threatened by the BPS report, because they know that depression is not a brain abnormality but wish it was.