Consumer-grade heat pumps do not approach the theoretical thermodynamic efficiency limit especially when the outside temperature is significantly below freezing temperature as that complicates design. Plus they do not last forever and it takes a lot of energy to make them. So a hybrid design with an electrical pre-heater for really cold weather can be the least consuming in the total balance of energy. But then one can just as well mine crypto currencies in the preheater just as the article described.