There is no reason whatsoever to believe that the financial carrying capacity of the US economy—-or any other DM economy—-has improved since the 1980s. In fact, it has gone the other direction in recent years due to aging demographics, declining competitiveness versus the surging EM economies, dwindling rates of productivity growth and a dramatic increase in the leverage ratio against both public and private incomes.
All of these adverse macro-trends mean that the US economy’s ability to generate growth, incomes and profits has been significantly lessened. Accordingly, since its ability to service debt and equity capital at an honest market rate of return has diminished, the logical expectation would be that the finance ratio to national income would fall.
In fact, once Greenspan took the helm and his apparently atavistic embrace of gold standard money melted-down under the Wall Street furies of October 1987, the finance ratio erupted. As shown below, it has never looked back and at 5.5X national income has reached a point that would have been unimaginable on the morning of Black Monday.
Stated differently, under a regime of honest money and market determined financial prices, the combined value of corporate equities and credit market debt would not have mushroomed by 8X—- from $11 trillion to $93 trillion—- during the past 27 years.