How exactly do you envision this going wrong?

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

That shelf is more glue and fire retardant than it is wood. Its also really bad as a book shelf so it might still be superior in this role than the intended one.

I once worked in a hardware lab that used wire shelving for holding arrays of running machines, and a bad ground running through one chassis caused anyone who touched the shelf to get shocked by something very close to line voltage.

I’m more worried about heat dissipation though.

You're not wrong.

How in gods name this article made it to the front page of HN is a mystery.

I mean, you can probably reduce any HN article to something that doesnt sound worthy of being on here if you want

I keep wanting to build this but I have seen people talking online that they changed the legs and they are now hollow and not really suitable for this.

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.