It doesn't even have to be a tech business; most random offices have a small rack in a closet somewhere with some networking equipment on it, and the whole thing usually sells as one lot to anyone with $50 and a screwdriver to remove the equipment from the site.
That has made me very cautious to use this for any serious amount of mounting.
Edit: Apparently there is a section on that page about it, but does not give a ton of confidence that it won’t give me a lot of issues.
I also had a Billy sat next to it, and did similar to this (but again not racked), with all of my AV gear inside. The door was great, it'd make any status lights diffuse and so they wouldn't interrupt watching a film in the dark (and my old Sky box used to have annoying blue LEDs with an animation when playing back a recorded show), but at the same time remote controls still worked through the glass. Literally best of both worlds. I cut a big hole in the back for cables, which also served well for airflow. I considered adding a fan, but never needed it. I suspect there would be issues with negative pressure doing that though.
How in gods name this article made it to the front page of HN is a mystery.
So the answer to the question of "how did it make it there" is exactly what I said, enough upvoted it that it made it to the front page.
As to "why" those folks upvoted it, well, on that I have no idea.
Oddly poignant. I can't be the only one.
See for example:
The rack itself won't hold electrostatic charge, and if the devices themselves want to be grounded they can be grounded through their power supply
And wood isn't that easy to get to burn unless you turn it into small particles first
I’m more worried about heat dissipation though.
It's a shelf and in the past few years it has not yet failed at holding my books.
However, when the shelf becomes multiples of that, then people start putting hardcover volumes or laying the book flat and stacking them high within the shelf.
It won't necessarily fail, but it can substantially sag with heavier loads.
This is an issue for boardgammers who are after larger and heavier shelf spaces which is why the Kallax shelving is much preferred. I'll also note that Ivar shelving is solid wood rather than particleboard.