It talks about Expert System Architecture Diagrams (ESADs) as if they are an existing thing. I googled that term, however, and guess what? The only place "Expert System Architecture Diagrams" is found is in this blog post or references to it.

Furthermore, it quotes a "prime directive" of ESADs, "When creating expert system architecture diagrams, always strive to truly inform your viewer rather than merely make an impression," but I can't find a source for that quote anywhere, except as a paraphrase of a 2020 post on the same blog.

A lot of the idealism is accompanied by hubris. The post turns up its nose at whiteboard diagrams hastily put together by filthy casuals using their actual hands. And it implies that unless you're constructing your system diagrams in YAML, they don't qualify as expert-level.

If you're really interested in creating useful diagrams for system architecture, there is a host of material out there that is more established and authoritative. Information design is the relevant broader discipline, but there are many sub-disciplines that pertain specifically to the visual representation of the design of software systems.