Because there was a time (1920s-1940s) when people believed that the fine shot produced an almost "electric shock" type death from so many pellets hitting the target at once.
I am not making this up. Zutz wrote about reading it when he was a kid, and about finding out it was basic BS when he got older-one of those theorys like tight chokes (shoots like a rifle) short barrels, baby magnums, long barrels or whatever, that writers of the day (not you, Larry) tried to sell folks on.
Most of the time, writers are salesman. They are trying to get you to buy something. While O'Conner was waxing poetic about the .270 Winchester, he was shooting his game with a 30-06. He usually didn't write about that, though. The examples are legion since the turn of the century, and most of them are pure garbage.
Zutz, as far as I have been able to tell, never tried to sell anybody anything, and while he has been called a writer of simple tomes, his experiences usually land pretty close to mine. He didn't typically use a dog for hunting, and his favorite load for ruffed grouse (not difficult birds to kill) was a stout load of #6s. He liked to find them dead where they came down.
I couldn't agree more.
Best,
Ted