The depressed programmer

Exactly, looking back at your code and seeing how much you've learned is definitively a good thing. Not so much if the cause is a "bad state of mind".

I'm pretty sure the author of the medium article was conveying an entirely different point. Namely, that they noticed they wrote poor code, some time ago, when they were depressed, not that they got depressed, now, when they saw poor code they'd written some time ago.

There's more of interest in this very brief article: the broader role of the state of mind of a coder as they write code; that coding might be more art than science; and where's the research in to these things?

These are familiar issues to me and I'm sure some folk in the game but the author is right that much of the industry seems to ignore them with presumed* profound consequences for the quality of code that gets written.

* What little science I'm aware of on these topics is generally weak. This may be because the industry is mostly ignoring them so there's no money in studying them but it's also clear that the things to measure (state of mind and quality of code) are really hard to measure in a way that leads to useful science.