I like the ability to store sensitive data in public repositories, it's especially useful when bootstrapping new IaC repositories, you don't have anything at the beginning of a new project so there is no place yet to store secrets, this is "a way" of doing it.
I know you can use tools like SOPS but I think the transparent approach offered by tools like this one or git-crypt really shine for many use cases.
Looking forward to hear your feedback!