I don't know anyone in the last 50 years that has a "boiler" system for heating their house.
My grandfather had a boiler and steam radiators in his house in Washington DC, heated by coal and stoked by an "Iron Fireman" automatic auger system, but I've never heard of a gas-heated boiler in anyone's house.
We were all fuel-oil hot-air systems when I were a lad, and now either gas hot-air or electric heat-pumps.
Just one of those things that make you say "Hmmm ....". We all like what we're used to, that's for sure.