It depends on what you mean by “traditional furnace” since there are many generations of technology in play here. The article talks about “boilers”, which are huge tanks full of fire and steam, usually in the basement of a large office or apartment building, made out of cast iron and attached to cast iron radiators in the living area. They don’t run on a thermostat and just pump out as much heat as possible. These are the type of systems you see in movies where they handcuff someone to the radiator.
They’re not at all what most people living in a typical single family dwelling would think of as a furnace, which may be a forced air or water-based baseboard radiator setup.
A heat pump can keep up with a traditional furnace type system just fine, but not a boiler system because the buildings with boilers are so old they don’t have much insulation at all.
“Boiler” is British English, “Furnace” is American English.
In Britain a boiler is a device in a single family home that provides heating by using gas or electricity to heat water which is then piped to radiators. It is also used to heat water for showers. Boilers can be quite small, many modern boilers are “combi” boilers that heat water on demand without a separate hot water tank. My boiler is the size of a suitcase.
Older properties generally have a boiler and insulated hot tank. This means that you need to plan your showers and heating requirements in advance by “putting the water on” to ensure there’s enough hot water in the tank.
Forced air heating is rarely used in the UK and people are generally not familiar with the concept.
A boiler essentially means the same thing in American English. And they do occur in America. They are just usually rare, and only remain in larger older buildings, or very old residential homes. Most buildings are forced air heated (gas or electric usually) or those more recently installing heat pumps.
They’re not at all what most people living in a typical single family dwelling would think of as a furnace, which may be a forced air or water-based baseboard radiator setup.
A heat pump can keep up with a traditional furnace type system just fine, but not a boiler system because the buildings with boilers are so old they don’t have much insulation at all.