Well,
Just in case you are serious...
If you did that, and they have any clue as to how to use
Cpanel/WHM
they could login to your control panel, and make very damaging changes, like change root password, and such.
If you used it that way, you'd have to &Login&, therefore they would be able to gain access to your root WHM.
not a good idea.
The Remote Key does it in the background, where they can't do anything, kind of like using a system call, you never see the action on in the browser, but the connection is made, and
just returns a response, then you do something with the response, but the browser never will visit the actual page, as far as the user can tell.
hth,
Richard.