Is that even possible when mortgages are leveraged at a rate of thirty to one and sliced and diced and bundled in every conceivable way?
Unfortunately, not quite. Our laws regarding these things are very primitive, which often means that you can be in perfect legal compliance, yet still commit some very severe fraud against the people you're making offerings to.
I find it rather unlikely that our regulatory system will ever catch up with the state of the art in finance. There's too much money to be made in the short term by shoveling risk off into the cracks and pretending on paper that it doesn't exist, and it's too easy to do.