Can you really pull a battery cable and the engine still runs?

What it's really bad for is anything that doesn't like higher voltage... It doesn't hurt the alternator any... But if you decide to try it hook up a volt meter and watch the number climb, quickly.... I've seen upwards of 70 volts... If you're just doing a brief off & on to see if the charging system is working it's pretty low risk, nut leave it off for a minute & bad things can happen...

Back in the late 80's auto manufacturers were playing with windshield De-ice systems... Laminated conductive coatings on the glass & circuits to isolate the alternator & direct the power straight to the glass... An iced over windshield would be ice free in less than a minute.... But when the circuity failed that full voltage would destroy all sorts of stuff....