Oh, I totally agree with you. Evidence is on your side as well. My Christian buddies trying to get people to live more righteously have a nice saying for it: Garbage In, Garbage Out. I gave them a pun Goodness In, Goodness Out for end result. Idea being you have to feed your brain the kinds of things it can build on to achieve the result you want.
Anyway, the effect has its basis in intuition: our unconscious or semi-consciuos mind. Intuition runs most of our thoughts, feelings, and reactions based on prior experiences and decisions. A researcher once connected this to depression when he noticed that animals put into helpless situations learned to act helpless even when the situation changed. He experimented with a sort of mental reprogramming for humans based on speculation that it was in our head in some percentage of cases. That led to cognitive therapy which cured quite a few people of depression. Its methods were quite simple: record your reactions to negative situations; identify whether you overstate the severity or pervasiveness of it; create a neutral or positive way to reframe that which isn't bullshit; take time to actually say and believe that; keep that up. Over significant period of time, habit takes over where you start coming up with less negative stuff or countering it in your head without thinking.
Random other examples. The optimism studies support that people similarly highlighting the good and margalizing the bad live longer, feel better, succeed more, and so on. They do something similar to cognitive therapy although positivity comes before accuracy. Proponents of meditation find that clearing all those thoughts out of their head for small amounts of time helps their mental state across the board. Also note that it's initially a painful process that takes work to do. Monks used to fight evil and negative thoughts by meditating on love and beautiful aspects of life. Stress management shows us even primitive tricks like smacking a wall saying "Stop!" can interrupt that thinking with a different focus area as a follow-up.
The anecdotes, behavioral science, and neuroscience all corroborate each other supporting the GIGO concept. Mental illness has a variety of effects on this but I've seen it help many with it. Techniques, effect, and length of effect varies considerably but it's rarely a "nothing will help" situation. The author could be applying such things but is hyperfocused on suicide, despair, negative thoughts, all the ways he will fail... Garbage In, Garbage Out.
What he didn't write is about all that didn't commit suicide, were kind of OK, were happy once they left the building, or rare few that didn't let others affect internal happiness. He didn't point out that some people have convinced management to tackle technical debt or do preventative work by putting it in terms they understand. We see a number in HN posts each month. He didn't show examples of software shops doing it better along with their methods in his recommendations to change structural problems he wrote on in prior essay. Didn't do that because he probably never looked for such positive counterpoints in the first place. Even the suicides are a questionable list with Aaron and Murdock being great examples of people tied to thinking & behaviors that will only screw them up. So many others fought for utilitarianism and ideals with a cut-off point that left them otherwise happy with their lives and away from B&E's.
So, if anything, this article proves nothing about the effect of software industry on developers or suicide. Instead, it tells us a lot about how one person thinks. It also confirms that focusing only on negative aspects of life will lead to depression and possibly suicide. It implies people should do the opposite. Additionally, they might consider putting a lot of effort into finding and moving into a better work environment.