This provides a mechanism for any client to identify and reject changes from any given remote that are non-compliant with the policy committed to the repo. So

This provides a mechanism for any client to identify and reject changes from any given remote that are non-compliant with the policy committed to the repo. So this is something that servers would certainly be able to use but it is also something that operates at the client level. And you could use it in environments where nobody uses the big hosted git platforms (github, gitlab, gitea, etc). So you could still use this in environments where you fetch changes to a project over ssh from a friend or cocontributor's dev machine. Or via basic, barebones read only https or ssh hosting. i.e. this is access control that works independent of centralized servers.