Correction: a single GFCI outlet on a circuit protects all outlets on the load side of the GFCI outlet. A GFCI cannot sense a ground fault on the line side.
If you want to protect an entire circuit with one GFCI outlet, it must be the first on the circuit.
However, it does confirm that the normal outlet by the toilet, protected as it is by the single GFCI outlet in the restroom (assuming the electrician wasn't as foolish as I was above) doesn't need to be replaced by a new GFCI outlet in order to plug in a fancy toilet seat.
If you want to protect an entire circuit with one GFCI outlet, it must be the first on the circuit.