[chrisjharris]

Well, those providing credit ratings (the rating agencies) were not the same as those selling the debt (investment banks). But more than that I think it's unwise to be so certain about intent - how do you know they were deliberately getting the ratings wrong, and not making a giant mistake? The rating agencies did very badly from the crisis, so it's hard to argue that they also saw the whole thing coming with premeditation.

I also think your explanation of the GFC overlooks what was an extremely multi-factorial situation. Most explanations would allocate some causality to changes in regulation, changes in global debt dynamics. Securitization aside, it was the peak of a huge borrowing/lending boom not unlike numerous previous financial market crashes.