I think what they meant was that it wouldn't have happened if the phone hadn't been plugged into an AC outlet which, in Europe, is 220V. (If the same accident happened in the US, they'd have said 110V.) The phone itself, unplugged, wouldn't provide enough current to electrocute someone.
In theory, a GFCI outlet would have prevented this. That's why the National Electric code requires them in kitchens, bathrooms, and garages.