Where are the X apps Resources default?

[jagginess]

Why are the X legacy apps resource files for system-wide settings stored in
/usr/X11R6/lib/X11/app-defaults?

I currently would like to know the reason behind this, on Debian, it is under
/etc/X11/app-defaults.

In order for me to change Xterm's white background and have it black as the system default, I don't like playing with scripts and have found a very convenient method under this short tip I added to fedoranews.org

http://fedoranews.org/blog/?p=661

I would really like to know why it isn't under /etc.. as they are quite seen as setting if you say, want to change settings for these apps.

jagginess