As in, a console/command prompt login? Ctrl-Alt-F1(through6)? Who cares? It's necessary on Linux because XFree86 has to work on such a wide variety of hardware, and doesn't plug and play, and thus breaks easily. Its neccessary for other Unixes only if the user isn't too careful about Xsession modifications. I assume that OS X's GUI is much more reliable about plug-and-play, so just launch a bunch of Terminal applications.