Nobody knows how large software products work

Large software systems at tech companies are poorly understood even by their own engineers. Complex features like enterprise controls, localization, and compliance requirements create intricate interactions that affect every new feature. Documentation struggles to keep pace with rapid changes, and many system behaviors emerge unintentionally from default choices. Engineers who can reliably answer questions about how software works are rare and valuable, as most prefer writing code to explaining it. The ability to investigate and understand existing systems is a distinct skill from coding, requiring comfort with uncertainty and summarization.