Why Do Water Heater Anoides Deteriorate So FAST?

OB, that link won't totally load for me, maybe it's just me.

As stated, the tank and it's electrical bits are grounded but that wouldn't effect the reaction with the anode rod. The anode is sacrificial, the reaction is based on the free ions in the water of the tank from mineral in the water and the material of the anode. The anode rod would undergo this reaction if it was placed in a glass jar with water (just less so).