Its an old law and in most states. Believe me I got ticketed in Iowa, Missouri and Idaho.
I was told its because older cars would begin to run rough when they began to warm up and the choke was still on causing them to jump out of park and take off. Early 70's Ford pickups were good for it.
By the way the tickets were under 50$ and didn't go against your license unless your vehicle takes off and causes damage.