Can we use this for changing node authors en-masse?

See 📌 Undo deprecation of UnpublishByKeyword and AssignOwnerNode action plugins Active . I think if you install the core Action UI module, you'll have it back, someone broke backwards compatibility by moving actions in core.

@graber, Thanks for the response. Yes, you are correct - I had specifically got rid of the Actions UI module because it is a deprecated module and so I didn't want to rely on it in the future.