The point is that a single line[0] and a minimal graphic could substantially improve the reader's comprehension while simultaneously providing them the necessary nomenclature to find relevant material to further increase their understanding.
Look at this line:
| One of the most important classes goes by the humble name “P.”
It tells us almost nothing, except of its importance. Only to be followed by | Roughly speaking, it encompasses all problems that can be solved in a reasonable amount of time. An analogous complexity class for space is dubbed “PSPACE.”
This tells us nothing... My first thought would by "why not PTIME and PSPACE" if I didn't already know what was going on.The whole work is about bridging these two concepts! How can we understand that if we don't know what we're building a bridge between? It's like reporting on a bridge being built connecting England and France but just calling it a bridge. Is it important? Sounds like it by the way they talk, but how can you even know the impact of such a thing when not given such critical context? You get tremendous amounts of additional context with the addition of so few words.