Why does "man x-terminal-emulator" return the output of "man gnome-terminal"?

I know what x-terminal-emulator is and does, but I don't understand why there isn't exist a special manual page for it instead to be redirected to the manual page of gnome-terminal. I would like to see a manual page explaining what x-terminal-emulator exactly does and in that page a reference to man gnome-terminal.

Is this correct (if yes, then why, for example, the output of man dir doesn't return the output of man ls)? It is there a good motivation behind this fact?

x-terminal-emulator is a virtual package. The terminal emulator is configured by Debian's alternative system.

On Ubuntu you can easily follow this symlink construction, e.g. for gnome-terminal:

$ which x-terminal-emulator
/usr/bin/x-terminal-emulator
$ ls -lF /usr/bin/x-terminal-emulator
/usr/bin/x-terminal-emulator -> /etc/alternatives/x-terminal-emulator*
$ ls -al /etc/alternatives/x-terminal-emulator
/etc/alternatives/x-terminal-emulator -> /usr/bin/gnome-terminal.wrapper*

Now regarding the man pages, update-alternatives also links the man page of gnome-terminal to x-terminal-emulator as explained in the update-alternatives manual:

   It is often useful for a number of alternatives to be synchronized,  so
   that they are changed as a group; for example, when several versions of
   the  vi(1)  editor  are  installed,  the   man   page   referenced   by
   /usr/share/man/man1/vi.1 should correspond to the executable referenced
   by /usr/bin/vi.  update-alternatives handles this by  means  of  master
   and  slave links; when the master is changed, any associated slaves are
   changed too.  A master link and its associated slaves make  up  a  link
   group.

Source