At the time of Lehman’s failure, half of all mortgages in the U.S.—28 million loans—were subprime or otherwise risky and low-quality. Of these, 74% were on the books of government agencies, principally the government-sponsored enterprises (GSEs), Fannie Mae and Freddie Mac.
I think that the left’s counter-narrative is that Fannie and Freddie bought the better mortgages of those available. What happened is that the really bad mortgages that they didn’t buy ended up defaulting, causing house price declines, which caused the better (or not-as-bad) mortgages that Freddie and Fannie bought to default, also.
In addition, the counter-narrative is that Freddie and Fannie were driven by their shareholders, not by their regulators, to buy risky loans. I would just note here, as I have before, that it is a bit perverse that we had the Fed tasked with consumer protection in the mortgage industry while HUD was tasked with safety and soundness regulation of the two key lenders. And we are surprised that this did not work out well?