"Nearly complete"? No matter how deep your knowledge is, you're only scratching the surface. To pick a small example, there's something like 20 TCP congestion avoidance algorithms alone (many are available in the mainline Linux kernel, and they can be picked depending on the task and network at hand), and I believe it took something like a decade of research, trial and error to solve the bufferbloat problem.
> No matter how deep your knowledge is, you're only scratching the surface.
I understand this is just emphasis, but no, its not magic, its not innate ability, its just software man! If you have dug deep enough, and understood it, that's it. Key phrase is IMO 'understood', but that's universal.
I think the point is that it may be impossible for a single human to have "nearly complete understanding" of how the networking stack work. But maybe what was meant was nearly complete understanding of the fundamentals. That's certainly achievable. But networking in the kernel is a beast of a thing with specialists in small parts of it. But I don't think there's a single human that know nearly all that those specialists know combined.
https://en.wikipedia.org/wiki/TCP_congestion_control
https://lwn.net/Articles/616241/