The thing that makes them not painful in bad times is that often the payments stay fixed, and the extra interest is tacked onto the end (meaning that you are gaining more to pay). (you can get a mortgage where the payments do immediately change as the rate changes)
That being said it is possible to hit the "trigger rate" where your fixed monthly payments are no longer even covering interest alone, and then the bank will give you a call to make your payments go up.
The people that get hurt the most with increasing interest rates are new home buyers with high-ratio loans, with their amortization already at the maximum. There are definitely some people who get caught in that squeeze and are forced to downsize or right out of the market by those conditions.
It's very common to always go with a floating variable mortgage and for the past 3 decades it's been the clear winner to locking in a rate for 3-5 years.
It also explains why last year the average sale price of a Canadian house was double that of the US. Let that sink in, in a country with higher taxes, lower wages and variable mortgages...the price is double.
It should be the other way around. You'd expect the US to be the same or maybe a small premium to Canadian home prices.
Most banks will give 5 years fixed at maximum and the interest rates were always higher than variable.
Most people signing for the variable rates didn't expect this sort of massive increase within a year, given its been fairly low for a decade.