As a matter of fact, government did.
If you read the article, you'll recognize that the banks were forced to take on poor credit risks and were threatened with regulatory consequences if they did not.
Indeed, banks were pushed to have a quota of what were referred to as NINA loans -- no income, no assets.
When the banks still resisted, Fannie Mae and Freddie Mac agreed to buy the loans -- transferring the banks' liability for bad loans to the taxpayer...en masse.
Then, in order to get more money -- to buy more bad loans -- it was Fannie Mae and Freddie Mac who packaged the loans and re-sold them, creating the mortgage derivative market.
It is because the banks were, in fact, doing their job -- trying to restrict loanss to buyers who were creditworthy that the government started distorting the market.
Even if CRA was a factor, it merely helped out people who were already in low-income 'residences'. There was no bubble in the hood.
Look at the areas, Las Vegas, Florida, Arizona, California, that is nothing but speculation. They gambled, and tried flipping houses, and lost.
I'll say again, it was the Gov't fault, and that was through cheap credit.
There was no Freddie Fannie or CRA in the commercial real estate market. Boom Bust.
People used their Mortgages as ATM's and bought shiny stuff. That helped drive the business cycle. They couldn't pay it back.