I'm pretty sure this is wrong. If I have a spare apartment and start renting it out, I'm creating wealth, not just redistributing it. So changing the pattern of who rents from whom should influence the total amount of wealth created.
Though I should clarify that when I talk about "the size of the economy" I'm talking about something intangible - the 'wealth of the nation', or more precisely the 'nation's rate of wealth-creation' - rather than simply GDP. Perhaps GDP will reflect the changing rents, perhaps not, depending on which type of GDP we're talking about (I seem to recall that there are several, including a 'spending' measure and an 'income' measure.)
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