Odd. I wonder if they have no experience with paperweights and they are amazed by the way the setup changes size and shape when they move it. I had a guest one time who was not fascinated by the intricate canes of my Perthshire collection but by the way they "moved" when the weight was turned.
I also wonder if the 40s attribution is because they asked an 'expert' of their acquaintance about it. It looks a little like the 30s Chinese weights.