Jenée Tibshraeny at interest.co.nz has written an excellent article on the issue of insurers underwriting people with mental health conditions. I think Tibshraeny does a great job of explaining the consumer position - even advocating for it - while explaining the industry position too.
There is a gap. Some people with mental health conditions may not be treated fairly in the underwriting process, and recent events are, maybe, changing the environment, and insurers are slow to change. They must be, insurers need good data before changing their views, or else they may be exposed to lots of new claims. In Australia there is a problem with income protection, and mental illness is contributing to that. For a complex issue to get covered in this way is both important and rare. I was glad to see it done so well. You can read the article at this link.
Stephen Potter, head of underwriting at Fidelity Life, did a great job of explaining the underwriting process, and in so doing, explaining how it is really good to have an adviser involved.