Why did the US Navy use turbo-electric drive in several warship designs?
Short answerIt improved machinery flexibility and damage tolerance by allowing surviving generators to power surviving shafts, at the price of extra weight and expense.
NotesTurbo-electric machinery separates generating power from the particular shafts that use it. In a mechanically linked arrangement, damage to a turbine or gearbox can disable the shaft connected to it. With electric drive, surviving generating machinery can supply motors on other surviving shafts even when its original mechanical counterpart is damaged. A single working generating set could provide balanced movement through several shafts, although at low speed. That redundancy costs weight, money, and construction complexity.