I think the claimed issue is that these people do receive income from those assets indirectly. My understanding is that if your assets are worth much more than the amount you're borrowing then a bank is happy to keep giving you loans, which you use like income, that incur compound interest until you die, your estate must settle up the loans, and the estate gets to pay capital gains against the basis when you died, not the basis when the shares were first created and worth $1 each.