Totally missed the point. Even with Code reviews, Unit/Integration Testing, Automated CI/CD and more can a person broke the prod.

One intern was told to deploy the app and I guess he made a mistake and updated k8 configs which deleted all the pods. Tell me how code reviews are supposed to catch it.

If you think "why not restrict config actions" etc, it's because the dev can go there and tweak those actions too. And each step added means less velocity of development. It's a game of cat and mouse. With isolation, you can limit the blast radius and loss of revenue.