there's pros and cons

using the same directory drastically reduces the amount of assumptions about your system's permissions and your own installation (or lack thereof)

old school *nix editors typically do something like emacs and vi typically do, whereas old WinDOS/Mac single-user systems would have an installation file and a cache system-wide, and post NT and OS-X they have roughly the same but in a centralised user directory that is not system-wide, but is located as if it were (different evolution path)