My guess is, that you redefine them to mean the semantically same in a new domain. What I mean is that gg and G lets you go to the top of the file and to the bottom of the file, right? But on the command-line, what is the top of your file? And what is the bottom?
I can only speak for the Emacs capabilities of readline: all commands which would usually change the line (previous/next-line, beginning/end-of-buffer) will use the history as the buffer. All of them preserve the line you are currently typing, which will be the end of the buffer.
