The idea of the resistor is that you deliberately design
the coil to operate at a voltage lower than 12 V and then usethe resistor to get to that voltage under normal conditions.
When you're cranking the engine with the starter the battery
voltage drops and hence the sparks get weaker. To combat this
you bypass the resistor as long as the starter is operating.
This gives you pretty much similar sparks during cranking and
normal operation. It doesn't matter if you're running
electronic or mechanical points, it works the same way for both.
Will this help:idea: