> trusted publishing doesn't solve that if you use self-hosted CI
Is there any particular reason for the whitelist approach? Standing on the sidelines it appears wholly unnecessary to me. Authentication that an artifact came from a given CI system seems orthogonal to the question of how much trust you place in a given CI system.
Well, given that Github owns NPM, one potential reason could be vendor lock in.
Also, from an implementation standpoint it is probably easier to make a system that just works for a handful of OIDC providers, than a more general solution. In particular, a general solution would require having a UI and maybe an API for registering NPM as a service provider for an identity provider of the package owner's choice.