Certainly up for debate, but personally I think it's a bit of both but much more the latter. But there is a flip side: a combination of some of our banking regulations and that conservative corporate culture are what saved our banks from the worst of the sub-prime mortgage crisis and financial institution contagion that disappeared or nearly disappeared a number of US companies (Lehman Bros, Bear Stearns, Merrill Lynch, AIG, Citi, Wachovia, Washington Mutual) and threatened the collapse of the global financial system.
For example, our banks did not engage in prop trading (betting their own money rather than their investors' money) to the same extent as US banks, and were permitted by law from using client deposits to fund prop trading activities; insanely, US banks were not prohibited from doing so, as a result of the mid-80s deregulation regime. After the crisis, the Dodd-Frank legislation made this illegal again in the US.
So that's about regulation. But Canadian banks technically were permitted to engage in some of the risky financial instruments that also contributed to the collapse of those aforementioned companies, namely CDOs (collateralized debt obligations, which packaged shitty mortgages and other bad investments in a larger financial product that was then given a higher credit rating than its underlying investments), but chose not to at scale.
So, to tie it all together, we should all be generally thankful that Canadian banks are as conservative as they are, at least when times are tough, but it also means that we aren't going to see a widespread change to the way they finance multi-family residential building construction anytime soon.