Not quite correct I'm afraid.
Here's my twa bawbees worth, or 2 cents in euromoney/dollars,
The ESC is a high frequency switching device that controls motor rotation in direction and speed/frequency by switching. A battery is a power supply, in our situation a DC direct current, +- potential difference, voltage device.
An ESC cares not one iota or jot where it gets it's power supply from.
i.e. if your ESC requires 11.1 volts or 55volts DC or any nominated value in between, you can arrange the power supply to have leads/conductors as long as required, provide you achieve the correct voltage at the ESC input terminals and have leads/conductors sized in area to carry the required current, Amps. I have personaly used extended power leads up to 40 inches / 1 meter in length. With no adverse effects so far. I would not, however extend the three leads from ESC to motor, as much, thats where the length would be more critical.
Modern ESC have the inbuilt and preprogrammed functionality to best guess the power supply type, by the voltage, i.e. NiCd, NiMh, LiIon and LiPo cells, it takes the voltage value and slots it into a preprogrammed value.
Now I may be incorrect, and would welcome an understandable explanation, but I wouldn't go as far as saying "Never" extend the power supply leads.