Who's to blame?

From the Curious Capitalist, quoting an academic paper

Most significantly, we find evidence that the changing credit regime that took place in late 2003, as the GSE’s pulled back from the market for political, regulatory, and market-based reasons [Curious Capitalist notes: they're talking about accounting scandals, caps on retained loans, etc.], is suggested to be a primary factor reducing the dominance of market fundamentals in affecting house price returns and creating the price-momentum conditions characteristic of a “bubble”. Rather than causing the run-up in house prices, the subprime market may well have been a joint product, along with house price increases, (i.e., the “tail”) of the economic, political, and regulatory environment characteristic of the early- to mid-2000’s (the “dog”).