The problem is not about replacing actors with technology. It is about replacing the particular actors with their computer-generated voice. It's about likeness-theft.

Agreed. I think the framing of "stealing" is a needlessly pessimistic prediction of how it might be used. If a person owns their own likeness, it would be logical to implement legal protections for AI impersonations of one's voice. I could imagine a popular voice actor scaling up their career by using AI for a first draft rendering of their part of a script and then selectively refining particular lines with more detailed prompts and/or recording them manually.

This raises a lot of complicated issues and questions, but the use case isn't inherently bad.