That S&L crisis back in the 80s featured mortgage-backed securities. If you want to see “them” at work, look back at what the press was saying while 2007-2008 crisis was unfolding. They acted like mortgage-backed securities where some new-fangled, never before seen thing.
How did the subprime package differ from the one he took? Variable rate?
Also, while we are on the subject of the 2007-2008 crisis. Who recalls that credit “reform” thing circa 2005 or 6? That was the pin that popped the housing credit bubble. IMHO.