Almost any lifestyle asset I keep in my possession could in principle be rented out by me instead, and so generates a virtual income or benefit, just as home ownership does. In principle why not tax my inherited artwork, car, or even clothing based on their rental value? In the same vein why not tax my education and other marketable personal attributes for the economic value they represent even when not being put to active income generating use?
That is the proposal. It's up to the government of the day to set a threshold for what is worth taxing and what is not