Mostly because most of the "one wire" vendors share a situation with Pinnochio- - - -one of these days they're going to have a long nose. In other words, they're lying. Some (not all)"one wire" alternators have different regulator internal wiring so those terminals on the perimeter of the alternator aren't needed. They usually have a rubber plug installed in the rectangular slot on the perimeter of the housing. If you've got one of them, just connect the heavy gauge charge lead and drive on. If the two blade terminals are exposed, wire the thing the way GM engineered 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!