You argument assumes inefficient advertising invades privacy less, which I'm not certain is true, or that an invasion of privacy is necessary to be efficient. Again since it wasn't really defined either way I suppose it's debatable what is meant by efficient or inefficient.

I would suggest that ideal advertising/marketing should have a viral or organically promoted component to it. I'm always going to be more likely to be interested in a product that someone I trust recommends or that I'm directly seeking rather than is being pushed to me. Efficient advertising would ideally be more passive rather than pushy and active and rely on and encourage organic promotion by having the right fit for the audience.

Still I'm just speculating what is meant here.