I would say that the debt-to-income ratio is just one ratio amongst many that are available to analyze the housing market. For instance, you have the debt-to-income ratio, the “net-worth to income” ratio, and also the debt-to-asset ratio, which looks not just at the income of an individual but also at the asset side. While debt-to-income ratios are quite high, the assets that are backing up the debts, which are largely used to purchase assets like homes, are also increasing in value. The net worth of Canadians is actually quite high.
The other thing to note is that debt servicing ratios have actually been coming down as a result of lower interest rates. My point in all this is just that you can't glom onto just one ratio. You have to look at the whole series of ratios.