Which I support.
But social, political, and economic conditions also play a big part in those two conditions, I think. If you are looking for non-physiological factors affecting human health, then political/social repression and exploitation, physical violence, and poverty – which are (or should be) primary elements of any biopsychosocial model – are all right up there, and there is no lack of them in this world.
These things will not be solved by better pills or psycho-behavioural therapies alone, though they have their place, at least for short-term management, and sometimes longer.
I agree that these things likely play huge roles in classic mental illnesses. Though I don't think one can be confident that there is not a very large contributing biological factor in all these diseases that could potentially prevent these societal factors from causing such enormous damage.
And there are so many subtypes of mental illness that one can't definitively say that "these things will not be solved by better pills". Sure, on one end of the spectrum, a perfectly healthy person can be subjected to weeks of terror during war, and develop PTSD, anxiety, and depression.
But on the other end of the spectrum, there are obviously "physiological" forms of mental conditions.
Drugs, like stimulants, hallucinogens, or drug withdrawal from opiates, can cause anxiety and depression in an otherwise happy person. 100% physiological.
I think I've read that numerous people have experienced post-infectious mental conditions such as OCD and tics.
These are just cases we've observed. We can't be sure there aren't genes we haven't found yet directly tied to a person's risk for depression or anxiety, where a pill can simply deactivate the protein causing issues. Or whether, like ME, pathogens lead to the majority of cases, the difference being the infections are caused by some virus that is barely noticeable as an illness and which happens in young children, so it seems like a lifelong condition.
Since ME happens so obviously after infection, there was an advantage there in motivating research into biology. But living with anxiety, I feel like this condition is something similar, but 50 years behind because there is no obvious infection. I'm trapped in here, with a deep understanding that there is something wrong with my body causing both ME and anxiety, and knowing that living in the most wonderful utopia possible wouldn't change a thing if my cellular environment was to stay unchanged. And like how people said/say of pwME they're "just being lazy" or "they're choosing to lay in bed, nothing wrong with them", and they're screaming inside, "you're wrong", that's similar to how I feel with generalized and social anxiety, or the OCD I once had, when people suggest therapy or a change of scenery will fix me.