Function of Ballast Resistor with Points Ignition.
Essentially as described above (protect points) and uses temperature to increase flow at higher rpms to offset reduced dwell time.
Attachment. 1969 Dodge Service Manual, page 8-46:


Function of Dual Ballast Resistor with Magnetic Pickup Ignition.
Chrysler Master Technicians Conference, "Ignition System for 1972," page 5

FWIW, the Ford Duraspark systems I've worked with on AMC Jeeps used a resistance wire to the coil instead of ballast resistor. The wires are quite long, doubled back on themselves whe needed to keep it within the harness loom. Using a wire presumably spreads the heat created over a larger distance, and sufficiently so it doesn't degrade the carrying capacity of the otehr harness wires.

In any event, if an electric pump is drawing power through the resistor either in Start or Run, this will be a problem.