> I agree it seems weird to call close to 100% efficient "terribly inefficient"

A lot of my winter and nighttime electricity comes from natural gas.

50-60% of the heat energy in natural gas can get turned into electricity and make it to my house.

Then, it can be used to heat my ceiling a light bulb, where almost half of the heat immediately escapes my home. This is not a very good way to heat my house, versus my high-efficiency natural gas central air system that is more than 95% efficient in using the energy in natural gas to heat my home: it's about 3x worse.

Of course, even more efficient would be to use the natural gas to make electric power that runs a heat pump. That could be 200% efficient end-to-end.