You might ask why mother mopar would go to all this trouble. I have heard it said that the gauges were originally designed for 6 volt cars. By reducing the average voltage to about 6 volts, they didn’t have to redesign the gauge system.
It seems plausible. It also seems likely they wanted some operational voltage that was sufficiently lower than a low battery would ever get so the gages would not be effected by the main system. So maybe a combination of factors.