I'd note that actual -35 days are pretty rare. Per Environment Canada Climate Normal Data from 1991 to 2020, Edmonton averages only 2.5 days per year with a minimum temperature below -30.
While you're correct, they do happen and need to be accounted for, and temperatures in the -30s in general aren't rare, but we're also experiencing more extreme weather as of late. Edmonton set a few records for cold the last few years, and those moments, when the grid is at the most strain, is also when the power is needed the most to keep people safe.