It actually would deal with the issue that led to the GFC.
The idea that it would become trivial to distinguish between good and bad investments seems to me to be incredibly naive.
It is not naive. It is exactly how smart contracts work.
If you purchase a CDO on a blockchain, you are purchasing a share of whatever revenue paid into another contract. You can monitor those contracts, and the ones that are programmed to pay into THEM, and the ones that are programmed to pay into THEM ad infinitum.
Yes. And this is impossible with smart contracts. You can commit fraud by pricing the asset, but you can't prevent the market from demonstrating its quality in real-time.
With smart contracts there would have been a housing bubble, but there would also have been an inflow of capital when the market-value of the majority of CDOs crashed below about 80 cents on the dollar.