Goes deeper than just IBM. Prior to DOS there was CP/M and CP/M had many programs with an older heritage. For example, it was possible to copy from a source (such as a file) to a destination (such as another file, or an I/O port) using a program called PIP (http://en.wikipedia.org/wiki/Peripheral_Interchange_Program). On CP/M, for example, you could print a file with the command (PRN: is the name of the printer device; at the time that was likely a parallel connected printer):

    PIP PRN:=FOO.TXT

PIP itself predates CP/M having been present on machines such as the PDP-11. Wikipedia tells me that it was first implemented on the PDP-6. For example, on the PDP-10 you could do:

    PIP DTA1:/X=DSK:*.*

which copied all the files from the disk onto tape. The /X there modifies the destination and indicates that file attributes (modification time etc.) should be preserved.

PS Now my memory is fully restored from 1980s backing store I believe that CP/M actually replaced the / in PIP with single character switches inside [] and that the route to / being switches in MS-DOS most likely comes through DEC heritage from the PDP series. For example, the W switches would ignore r/o set on a file and overwrite it. This would copy all .COM files (i.e. executables) from B: to A: and overwrite without warning:

    PIP A:=B:*.COM[W]