There are enough professional reports of electrolysis problems out there in trade journals to make this a real, and growing, problem. It occurs when engine and chassis grounds are corroded so that voltage potentials build up (even to .25 volt) between the engine or radiator and ground. High current loads running through corroded grounds exacerbate the problem. The coolant can then act as a secondary ground because it is conductive. In so doing, the aluminum parts especially act as a sacrificial anode and dissolve.
To measure this, start the engine, place a voltmeter in the coolant and on ground, and measure potential. Turn on all power accessories and measure again. High readings mean you've got a problem, to be cured by de-oxidizing and protecting your ground connections.