And back then, pretty much any civilian vessel could be transformed into one of these...The people who wrote the US Constitution lived in a time where...
...Besides, do you really believe the US government could pay ANY private-sector firm enough money for them to go toe-to-toe with an organized, well-trained and well-equipped enemy force...
And, lastly, do you really believe that, if the private-sector firms had effective armies and the government did not, the private-sector firms would meekly obey the law and do what the government tells them?