A platform team renamed subnet outputs in a shared network stack and accidentally broke twelve service stacks that referenced the old names. The network update was technically correct, but the stack output had become an undocumented API. At scale, consumers depend on outputs with the same expectations they have for a service contract.
Without following this practice, teams typically discover the problem during a production incident. The cost of fixing issues reactively is 10-100x higher than preventing them proactively. This becomes especially dangerous at scale when multiple teams depend on the same infrastructure, because one team's shortcut becomes another team's outage. Organizations that skip this practice often find themselves in a cycle of firefighting instead of building. The pattern is predictable: it works fine in development, survives staging, and fails spectacularly in production under real traffic and real failure conditions.
