My point really was that if you have access to insert a disc the security requirements are different.
Out of the box, with no extra effort to 'secure', *nix beats ios beats doze from a remote access standpoint.
And, securing a machine against a bootable disc (round or usb) is OS independent.
If you can socially engineer access (click here for nudes), that's a whole lot easier than brute force entry too...
Bootable disks take too long.
It's not really brute force... Open a terminal window (or command prompt on Windows or MacOS) and type a one line command. Instant remote shell access. Without a password. At that point, there are hundreds of ways to make the shell persistent and escalate privileges. And it's easier to access other machines on that network than it is to access the first one remotely.