Are there any software projects of that size that are clean and well-structured? The larger a codebase grows, the less tractable it becomes. Refactorings are h

Are there any software projects of that size that are clean and well-structured? The larger a codebase grows, the less tractable it becomes. Refactorings are harder, more expensive and riskier. Also, more developers means more attack surface for inconsistencies and crappy code of someone unmotivated.