Rubbish design from the 1960's compared to what exactly ?
Fast tickover compared to idle tickover to put a charge into a nearly flat battery is the same you say.
Can I suggest you experiment on your suggestions with a modern alternator with both a voltmeter
and an ammeter connected.
Then come back to report that the amps produced is exactly the same at both idle and a high idle.
Volts is only half of the story