Watercooling has one benefit: The heat capacity* of all those water is amazing.

*Heat capacity = how many joules of energy the whole system takes to raise the system's temperature by 1C.

So, the CPU is generating x Watts of heat = x Joules of heat energy per second. Watercooling can absorb a LOT of Joules before the cooling system's temperature increases, thus helping in keeping the CPU away from its MaxTemp.

Plus when attached to a sizable radiator, watercooling system can release all those energy to the environment faster, thus reducing the effective energy absorbed by the system.