The lipo does not need and protection, as it is a battery and it has its own natural ability to absorb voltage spikes, thus eliminating them.
The ESC does not have this capability naturally, since the FETs is a voltage sensitive device, and they can NOT absorb any current in the backwards direction, nor in the forwards direction when closed. Hence do they need assistance from a device which can absorb these spikes.
And thats why the ESCs has its capacitors, while batteries does not.