Pit bulls have existed in the US for a long time, but only relatively recently have they risen to prominence as "killing machines". Before pit bulls, Dobermans received a lot of press as killers. Before that, German Shepherds were demonized. In the case of the German Shepherd, the dog's own massive popularity may have been to blame because of the resulting overbreeding and ownership by people who had no business owning dogs.
"Pit bull" isn't a breed, but a dog type encompassing the American Pit Bull Terrier, the American Staffordshire Terrier, and the Staffordshire Bull Terrier. "Pit bull" as a type also includes mixed-breed dogs which have pit bull characteristics. Pit bulls are still one of the most popular dog types in America. If they are truly the "killing machines" which can "snap" at any time, I would expect the number of maulings to be far greater than what we currently see in this country.
The analogy didn’t fail. You simply refuse to accept it’s applicability and so are caviling.
And save your pedantry. “Pit Bull” or “Bulldog” is a local colloquialism for the type of dog under discussion.
Good Luck.