I am struggling to understand the point this guy is trying to make. He’s upset that the system works, and he’s upset that it’s doesn’t require immediate manual intervention at every step. Is it just the nostalgia talking?

To most of us, an operating systems is means to an end. We use it to do work, or play games, or whatever else you want to do. If anything, Linux overall is in the best state it’s ever been, and it only continues to improve.

If the low-level manual work is what he wants, then there are certainly options he can adopt into his workflow, but outside of that, it just feels like aimless anger

Slackware is what Linux used to be.
Cause it didn’t really change at all since the beginning.
Still the same structure under the hood, still comes preinstalled with twm (the original default window manager for X, developed in 1987), if you want it to look like it’s 30 years old.
The distro is even still maintained by the same guy who created it.

But contrary to Haiku it works as a production system in the modern world, too. It has KDE, Wayland and a modern Linux kernel, and you can install optional helper tools that manage dependencies, Flatpak support, Steam…