The loans are out there. Based on lender risk/reward, people with high credit scores who want to buy a primary residence are a risk that the lending industry is willing to take for a full doc loan.
They are in the lending business. The fact is that in the past the vast majority of people with high credit scores have not defaulted on their loans, even when upside down.
Of course they are going to have losses, and the next few years will be a test of their guidelines.