But only for the 4 weeks a year you spend in unusually cold weather, the other 48 it's more efficient.

It's not like truly arctic places are a reasonable application but the overwhelming majority of our population lives south of Quebec and north of Wellington. So it's not a relevant point, everyone in the Arctic can just use resistive heating or burn fuel, and if we get everything else on heat pumps we reduce our enegy use by a factor of 2-3 regardles.