In a sense you are correct gore, a single user on a machine is very secure even though MS DOS has absolutely no file access restrictions in it. You can't lock out a file or restrict access to rights. I have a dos machine, get this, it's used to dispense money. Of course anyone can walk up to it and do a few key combinations to access the program but heh, it's like 20 years old. The OS is OLD. Most of the time to use DOS you must go to junk stores and garage sales to buy old equipment with drivers or basic PS2 stuff. You can accomplish the same type of security by just taking a nic out of a linux box and removing all but the very basic and necessary programs. Or go back to the older kernals?

//Edit there is a tcpip stack you can add to DoS to connect to a network. The older networks were nothing but dos connected to a lan built around coax and connecting to Novell. Version 5 is a long way from earlier versions. The stack may be built in? I like to retro games once in a while so I still have a dos gaming machine. You can even get a dos emulator to play on new windows boxex. I use DOSBOX to play old Sierra retro.
Some of them are still fantasic and you can buy a whole box of them for like 5 bucks.