Not true at all. That bubble happened precisely because of regulation. Banks were practically forced to lower lending standards by Freddie and Fannie, not to mention the FED key interest rate affected mortgage rates to get artificially low enabling many to borrow who couldn't afford it. All Wall Street did was feed upon this circle and meet a demand that was created by the government and no one else. It's called moral hazard, look it up.
Try reading this:
http://www.pbs.org/wgbh/pages/frontline/business-economy-financial-crisis/untouchables/blowing-the-whistle-on-the-mortgage-bubble/All the pressure to lower standards was coming from higher up inside the companies. If they'd wanted to not buy these loans, they would have jumped on the chance to use underwriting standards to block them. And you'll notice they stopped buying them when the bubble burst, nobody was forcing them to buy. Both the government regulation, AND the self-regulation failed to change behavior. But you can see that attempts at discipline were ignored or lied at to avoid.