That's not exactly what the article says. It just says that the police forces were largely privatized and part-time. Naturally that changed as the country grew.
This feeds a strange notion that society was just fine without police. It wasn't.
> It just says that the police forces were largely privatized and part-time.
That's just disingenuous. These "police forces" were nothing like anything we have today, either in degree or kind. I don't know the name of this particular fallacy, but it's when you imagine something from modern life must have existed previous to this era, if but more primitive. There just wasn't any equivalent.
If we could time travel and go experience the late 1700s, we wouldn't say "oh, so those sheriffs and those US marshals were the police, I didn't recognize the uniform!". We'd be amazed and disturbed by how different life was in that regard.
This feeds a strange notion that society was just fine without police. It wasn't.