In areas that get cold, you can't just use a heat pump. Residential heat pumps are only good to about 20 to 25f.
That was true a couple decades ago, but hasn't really been true in a while.
A combination of inverters, variable speed compressors, vapor injection, and using slightly different refrigerants means there's a number of cold climate heat pumps on the market that will heat down below -13°F.
Call him a Nazi, he won't even frown "Ha, Nazi, Schmazi" says Wernher von Braun