Understanding a system starts with following one thing all the way through. A user taps a button. Somewhere in the code, something wakes up because of it. Knowing where, and why, is the whole map.
You do not need deep knowledge of every part to see this. You need curiosity, and the habit of switching between the user's seat and the developer's until the two line up.
An agent can draw that map for you in seconds. The drawing is not the point. The walking is, because walking is how the model forms in your head.
A map you were handed shows you where things are; a map you walked shows you what to ask.
Kay
P.S. See one tap on Instagram followed through every building block, so you can walk the path yourself. https://systemthinkinglab.ai/learn/building-blocks/how-instagram-works/