Yes, deep down it is all chemical processes but complex systems can develop emergent behaviors that can not be explained by looking at the lower levels.
A few days ago, this article[0] has been discussed here on hacker news. I shows how the naive theory of chemical imbalances can be harmful for treating Schizophrenia.
> In this vision, mental disorders were best understood as brain dysfunctions that could be traced to abnormal genes. Schizophrenia stemmed from an imbalance of the neurotransmitter dopamine. Depression was a serotonin imbalance. Bipolar disorder was a lithium imbalance. ADHD a deficiency of norepinephrine. These conditions, of course, could be triggered by life events, but they were ultimately biological. It was a reincarnation of the ancient Greek humoral theory, which saw the various forms of madness as imbalances in the four humours: blood, phlegm, yellow bile, black bile.
I recommend reading the whole thing but I really liked this part of linking it to the Greek humoral theory.
In the end of the day, there isn't any scientific evidence that it is "just chemical imbalances". The reality is more complex. Medication has its place and it absolutely can help but it just one tool to help patients.
There is a good reason the brain disease narrative is so tempting: It avoids having to look at environmental factors. It avoids having to talk about how society is driving people mad. It is easier to say someone's brain is broken than having to talk about societal issues. It also leaves patients powerless, giving them the idea that their brain is just "broken" and they can't do anything about it instead of giving them the tools to create a better life for themselves and others.
In the end of the day we are all a parts of interdependent systems that form society. Mental health issues are more often than not societal issues more than individual issues.
[0] https://aeon.co/essays/how-the-psychiatric-narrative-hinders...