Anytime a charging circuit is interrupted the generator or alternator tries to overcome the resistance created by the open circuit. That makes the voltage spike to unreal levels, at least momentarily. If anything like a solid state circuit, or even a low-amperage fuse gets hit with the voltage spike it will burn out. Since electric current travels at approximately the speed of light (186,000 miles per second) it's impossible to disconnect and reconnect a circuit fast enough to beat the spike. Generators don't get damaged as often as alternators, but it's still possible to trash a regulator by doing the cable disconnect thing. Just don't do it!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!