There is a difference in terminology here that probably creates some miscommunication.
When diesel generator drives electric propulsion, what we have is in essence another type of transmission - mechanical, hydraulic and sometimes electric. It has its advantages and disadvantages, I am sure.
This is not the same as true electric propulsion - which really isn't so much about the motor but about the fact that energy is stored not in a form of liquid combustible fuel, but in a form of electricity stored in a battery.
The former is a viable transmission option. The latter is not viable at the current level of battery technology.