I see that as only half the story. While 0% loans were filling the coffers of Bank of America and Sallie Mae and Chase and Wells Fargo, those same banks were turning around and loaning the money out for consumption at 25% or for assets that rapidly depreciate like cars and TVs at 5-25%, or purchases of questionable value like college tuition at more variable rates.
r > g is still something of an open question in my mind, but the economic weaponization of debt and the inability of consumers to shield themselves from its adverse effects seems to be the reason for the wealth gap and why the increase in capital returns has payed better than overall economic growth, effectively transfering the future wealth of the poor to the present assets of the rich.
It could probably be solved in a generation with stricter regulations on consumer lending and the conversion of social security into a mandatory 401k, similar to Australia's "Super" program.
The fix for capitalism is to force everyone to be capitalists.