CloudFormation manages related resources through a stack. A template describes desired configuration; stack events describe what happened while the service tried to apply it. Validation checks template structure, while creation and update change the account. Neither validation nor a partially completed resource list proves that the stack reached its intended state.
Stateful resources need deliberate update and deletion behavior. A compatible configuration update should preserve the resource's physical identity and data. A failed update should retain or restore the previous working state, with events that explain the failure. A Retain policy can leave a resource after the stack is removed, so that resource still needs an owner and a later cleanup decision. These local tasks test the resulting account and stored object, rather than accept a successful-looking command alone.