Least privilege limits the damage any one compromised account, mistake, or rogue process can cause. An office manager who handles billing does not need access to tax files. A backup service needs to write backups, not delete them, and an AI agent that drafts emails does not need permission to send them unreviewed.
Applying the principle means reviewing access regularly, removing accounts and permissions that are no longer needed, separating administrative accounts from everyday ones, and scoping integrations and API keys narrowly.