Ballast Resistor
......And your point is? ........ The definition of ANY electrical ballast is pretty much that........it stabilizes current/ voltage/ power going to a load. In the "vacuum tube" days there were various ballast 'tubes' for various purposes
Just like ballast in a boat/ submarine it stabilizes "the vessel."
But that is not it's ONLY purpose. When you crank the engine for starting, especially in "the old days" "in the cold" "in the winter" and when the battery might be a bit down, obviously the old style "wound field" starters drew more current than the newer PM starters. Before the advent and popularity of multi-weight engine oils, that could be a factor. So when cranking, battery voltage goes quite low
If you just ran a 12V coil off the battery with no ballast, it would "see" greatly reduced power during cold cranking
SO THE BALLAST RESISTOR SYSTEM is bypassed during cranking and supplies "full" battery voltage to the coil which gives you a much hotter starting spark.