No one understands everything here. When it comes to software development, everyone I know says they're only really knowledgeable about what they work on. Most other areas, they'll have at best some passing knowledge of. It's like how doctors become specialists in just one part of the human body. There's maybe 5 people in the world are are a qualified dermatologist, endocrinologist, neurologist, and cardiologist at the same time. It's the same thing with engineers.