I had a college professor who used to rail against this very issue. He used to frame every human difficulty imaginable in existential terms, then talk about how tragic it was that "authenticity" got pathologized as illness in our culture.

I spent three years convinced I could solve my problems if only I read enough Kierkegaard. I got worse.

People have the right to couch their issues in whatever terms they'd like. Not everybody finds the idea that they have a "disorder" requiring "treatment" offensive. For some, it's an incredible relief to finally be able to think about their problems as caused by a medical condition rather than an existential inevitability or moral failing.