Earlier quoted context omitted.
> Canadian banks has a very conservative “stress test” ... Therefore it isn’t possible to “stretch yourself beyond any reasonable limits” “stretch yourself beyond any reasonable limits” means that you may not be able to pay your mortgage, it doesn't mean the bank won't offer it to you.
The bank won't offer if you can't pay, at least in the US these days. But we have 30 year fixed mortgages, I think Canada is shorter
The bank will look at how much you earn and how much you owe and say "We can pre-approve you for $X at Y%". They consider that you can pay that rate and they are most likely right.
Now if you do take $X, you have effectively leveraged your entire earnings, which for most people is a pretty bad idea because stuff happens and you can end up with a mortgage you can't pay because turns out you also want a car.
That being said (at least in Canada), your broker won't really let you take the full bank offers, or at least they don't expect you to do it.