Surprisingly to some, this is neither a law nor true. A complex system with a good workable and testable architecture will work, starting with passing the test

Surprisingly to some, this is neither a law nor true. A complex system with a good workable and testable architecture will work, starting with passing the tests down to satisfying the user... Such systems are not designed in detail but in general, and usually start with a single, simple but powerful overarching idea, which is actually quite complex to implement, but ends up working evidently well once even halfway done. Examples would be message passing architecture, event driven programming, time tracking, microservices, reactors, literate APIs, contract programming, Model-View-* and more... Note how half of those deal with reducing coupling by adding complexity.