Now that I understand more about how GNU/Linux distributions, display
managers, and X sessions work, it makes sense to separate meta packages
based on environment used.
When you use a display manager, you're just starting X in a fancy way.
Since you can run any program you want on the X server, it is easy to
install multiple desktop environments on the same machine and switch
between them easily, provided your setup is adequately modular (which
it should be by default).
