What I would like to see is a Windows challenge, where they try to achieve privacy as close to out of the box linux as they can get. That would probably genuinely be entertaining.

I get what you are asking for but I don’t think it is even necessary to have a list of users on the client in the first place using the MPA approach. I would guess the list of users is just available to the server, which pre-renders HTML out of it and provides it to the client.