It can be diagnosed now

Sure, but depression and immune system seem to be linked, so how do we know we aren't just more clearly separating viral components in boughts of heightened depression?

Personally I think our relationship with flu tells us a lot about the difference between our claimed ideals and our actual behavior as a society. We didn't want to know anything about it for curiosities sake and we invented all sorts of higher priorities to not study the mundane diseases between pandemics.

Well, how is a doctor who doesn't even know about it supposed to either diagnose it or rule it out? Depression is also something you cannot just reliably diagnose from a blood sample or something, so just going "depression!" as soon as someone starts talking about brain fog and being listless seems unfair. Most Doctors think in categories, they don't want to challenge what they already know and have been practicing for years. So the most important thing now is education, spreading awareness.

judging by my wife's experience, a woman could go to the ER with a gunshot wound and leave with a prescription for an antidepressant.

I don’t want to be rude, but have you looked into the established scientific knowledge which has accumulated on the impact of SARS-CoV-2 on the human body?

I really truly don’t want to be rude. I only want to point to the existence of literature on this.

There are results from molecular biology, from the various medical specializations, from population-scale studies.

There are certainly symptoms and biomarkers. There are documented changes to physiology, and there exists at least some information on how to help the body recover.