There are absolutely people with bigger problems than depression. For example, I have MS, and my mental health is absolutely one of my less concerning problems. There are so many options for mental health + the treatments are much easier to access than a lot of my symptom management meds + DMT. People undergoing chemo. People with ALS. People with bipolar (who can't take a lot of first line depression treatments) or other more complex mental health issues like schizophrenia.

None of this is to downplay depression, but there are absolutely people for whom 'just depression' would be accurate. Migraines suck, but someone with cluster headaches might call them 'just migraines' and they wouldn't be wrong.