interesting car craft article this month on GM modules

Well, there was more to it than that, BS. The manufacturers could have all used "direct 12 v" coils like, say some tractors.

But what the coil / resistor combo gives you is the ballast is just what it implies, as it's not a "plain resistor," it's a resistor that BALLASTS, IE as load current tries to go up, the ballast heats up and tries to bring current down.

The second thing "having a ballast" does (back in the points days) is that on that cold wintery, nasty day, when the battery is low and the 40 wt oil is like molasses, when you twist the key, the coil now gets "direct battery" power for a better starting spark.