I completely agree. The structure of our society actively deprives people from human connection which is essential to happiness. Individuals do suffer from depression at different rates, but it pops up the same way popcorn pops when you turn the heat on. The direct cause is the atomization of modern life, not some chemical imbalance in the brain.
The reason people treat depression as an individual problem to be addressed by individual means (medication) is that we are totally unwilling to acknowledge the complete emptiness of modern life. And also because modern life teaches us to treat everything as an individual problem. The symptom is itself the mechanism.
While lack of human connection can be one cause or contributing factor for depression in individual cases, and may make a lot of people "depressed" in the informal coloquial sense, the notion that major depressive disorder across the spectrum and across society is singularly caused by lack of human interaction (or singularly caused by anything at all) is not a notion evidenced by any literature on depression I'm aware of, and is not a notion espoused by any of mental health professionals I've encountered who routinely successfully treat people with depression.
Of course therapists don't define it that way... their definition is limited by what the treatment options are. Those options basically amount to prescribing drugs or becoming a friend for hire, not changing the structure of society.
And there are plenty of therapists (and researchers) who would definitely say that the quality of the relationship with a depressed patient makes or breaks treatment, in many cases it actually is the distinguishing factor. At the very least, it's a necessary one.
"The literature" isn't even clear on what major depressive disorder is. Well, the clinical definition is clear: literally sadness/low mood for at least 2 weeks. But what does that mean?
I guess what I really mean to say here is that we have essentially created a situation where people are pushed toward being alone. Then when a whole bunch of them feel empty about their state of being, we assign the label of "depressed" on them and give them drugs that are only barely effective. The lucky ones can afford to buy someone who basically takes the place of a close friend or parent. We have no framework to describe this state of affairs because every single one of us only has our permanently modern society as a point of reference.
It's easy to forget that the human brain is not designed to live the way we live. It's designed to spend every waking moment together with a very small group/family, always outdoors together, always doing something entirely tangible and physical together. Seeing a stranger was a rare occurrence. Imagine that!
"Sadness" happens when someone close dies. "Depression" happens when a huge number of human relationships that the brain needs get replaced by vastly inferior alternatives -- coworkers, social media, video game friends, service workers, etc. Nothing else but modern society creates this.
I think the quality of the human connection is important. The Dodo Bird Verdict[1] states that the relationship and connection between a therapist and client is the true healing factor. Indeed, a strong causal factor on client outcomes is the attitude of the therapist; whether they are warm, caring and genuine. The therapist-client relationship accounted for 7% of the variability in outcome, whereas adherence to a specific treatment accounted for 1%.
On an individual basis, the specific treatment matters, but statistically the human connection matters more. Your standard “what did you do on the weekend” friendship won’t cut it.
The reason people treat depression as an individual problem to be addressed by individual means (medication) is that we are totally unwilling to acknowledge the complete emptiness of modern life. And also because modern life teaches us to treat everything as an individual problem. The symptom is itself the mechanism.