My own part of the system I can build cleanly. But the moment my work depends on another team's service that keeps changing, and they depend on mine, and nobody's schedules line up, I'm lost. Writing my code is the easy part; untangling everyone's dependencies is what overwhelms me.
More people experience this than they realize.
You can build your own piece, but coordinating other teams and their dependencies overwhelms you.
If this sounds familiar, the Library can help you find the bigger picture.