The neurological field has grappled, over the last few decades, with an increasing understanding of the interconnectedness and pliability of the brain and the rest of the body. We've gone from categorical localization of function to neuroplasticity for example, and likewise we've seen how distinct disorders can involve a number of different physiological differences and deficits (comorbidites are rife, e.g. see atopy + neurological sensitivities). The brain is especially complex. Our grappling with the terminology around its disorders is entirely ok IMHO. It's important to not get tied down in dogmatic categorical thinking. It's also important to let people explore different treatment paths, and find what works for them. There is never going to be a canonical "cure" for depression, just as there won't be for IBS.
