A script that says "create 3 servers" makes 6 if you run it twice, because it does not know what already exists. Declarative tools like Terraform let you describe the end state, and they work out what to add or remove, so re-runs are safe. Imperative scripts still fit one-off tasks, but for long-lived infrastructure the declarative style avoids writing your own update and delete logic. Expect to explain idempotency and why it matters.