Well technically they are using households that way here too, it's just that they're looking at the overall total household net worth, so the actual number of h

Well technically they are using households that way here too, it's just that they're looking at the overall total household net worth, so the actual number of households doesn't matter. But start looking at the average amount per household, a closely related statistic, and now we're back to the same problem that combining/splitting households affects the figure.