

I think detecting that something bad is happening, finding out how, and stopping it prevents other people from being affected. Otherwise contamination incidents could go on for years, and the cumulative exposure to affected individuals would be higher, and the number of individuals affected would also be higher.
I think it was a 18th century British fad that spread to America - for example, look at the date on this London newspaper from 1734:
It didn’t make it into legal documents / laws, which still used the more traditional format like: “That from and after the Tenth Day of April, One thousand seven hundred and ten …”. However, the American Revolution effectively froze many British fashions from that point-in-time in place (as another example, see speaking English without the trap/bath split, which was a subsequent trend in the commonwealth).
The fad eventually died out and most of the world went back to the more traditional format, but it persisted in the USA.