Question on starter wiring

[AusTx68]

So there are three terminals on the starter. A large terminal for the positive battery cable, a small one for the purple ignition wire and the other large terminal that powers the starter motor. This terminal also has the yellow wire which leads up to the coil then splits off to the fuse box thru a resistor wire.

The way I understand it, when the ignition key is turned to START, power is sent thru the purple wire which activates the solenoid which engages starter motor. Power is then sent up the yellow wire to the coil providing 12 volts. Once the motor starts all power is killed to the starter and the resistor wire feeds 9 volts to the coil to keep the motor running. right? (68' C-10)

Assuming all above is correct, I wired up my starter by replacing the yellow resistor wire with 20 gauge yellow wire. That way I get a full 12 volts to my Mallory distributor which calls for 12 volts. The yellow wire also goes down to
the starter as originally wired up. Not sure that was even necessary since I am was getting a full 12 volts from the fuse box.

With the new wiring, when I turn the key to the ON position (not START) the starter makes a winding noise then promptly blows my fusable link. I ending up cutting the wire from the coil down to the starter. This all made sense since that yellow wire was sending voltage to the starter on the side that engages the starter motor.

So finally here's my question, Why doesn't that happen with the OEM wiring?? You would think that power to the coil would also send power to the starter motor right?