Incidentally, I think there is at least one important area where Knuth is actually still ahead of off-the-shelf libraries as of 2020: "broadword computing". When skimming volume 4A for semi-recreational purposes a few years ago, I was surprised to find multiple "bit-hacks" which were better than anything I had found in other sources, and proceeded to use them in my own open-sourced work. Every time I've encountered a situation where bitvectors are useful, I have benefited from rolling my own implementation.
Came here to say this. It's rare that you want to consume these things through an abstraction layer: the layer is often heavier than the work underneath. Sucks for readability, though, so I usually spend as much time documenting as implementing.
