“Bottom Line: Housing today is more unaffordable than in 2006, especially in the major Case-Shiller 20 metros.”
That statement — from the beginning of the OP’s linked article, and bolded there too — is wrong. Housing was WAY more expensive vs. incomes in 2006, both in terms of purchase prices and (especially) monthly payments. (Reference for SD).
So my reaction is: when the “bottom line” has a well known and documented fact completely backwards… well, that’s not a good start.