That’s a misleading number. In most other cases where we are using electricity–motors, CPUs, lighting, etc–we consider the heat generated to be inefficiency. It might be more accurate to say that electric resistance heating is 100% inefficient.

If you’re using resistance heating to heat your home, using electricity that’s originally produced by natural gas, then you’re using more natural gas compared to burning that gas for heat directly in a home furnace. Now, electric resistance heating can be a choice when it’s fed by clean electrical sources otherwise. Even then, though, you would prefer a heat pump if possible.