I am a lead on Kargo. That's a great approach you've described and Kargo helps you make that approach work even better. It's not trying to re-solve problems that are already solved well by config management tools or by Argo CD. It provides a higher layer that integrates with those to orchestrate the progression of changes from one environment to another...

So in your example, suppose you changed something in your Kustomize `base/` directory. With _just_ Kustomize and Argo CD, those changes roll out to all environments all at once. With Kargo, you can progress the change and (re-)validate it environment-by-environment.