It doesn't really answer my question, but from what I've seen in the TOC I'd say it's equivalent to an introductory course on computer architecture + computer systems and some cryptography as well. Kind of an introduction (don't get me wrong with the word 'introduction', it covers a decent amount of material) to the most important concepts and technologies that guide computers and the internet.
Most normal people and junior devs would get a red head when reading it, techies and seniors would nod along and sometimes say "uh... so that's how it really works". It's in between but a good primer on the essentials.
But regardless, my point was that there are many many things that people say every programmer should read, and that sometimes includes Knuth. In fact, so many things that even if I stop everything I'm doing and just keep reading everything "every programmer should read", I will die before I finish.