When writing the article I was debating going in deeper on the poor performance of the rating agencies, especially with regards to how they vastly underrated the amount of risk that traunched mortgage products had. However I figured that the base of the problem was what I would address, which was that ultimately subprime mortgages were being offered in high numbers. Youre right that if the mortgage products were properly rated, we would have seen a far less amount of investment into them, but at the time the speculation on the housing bubble never crashing was so crazy, that people were okay with defaults because they figured the price of the house was always going to keep going up.