For example try to use tab and the arrow keys to move
the
focus between widgets in a GTK app. You will find the
behavior is completely baffling and inconsistent, for
example a different series of tab/shift-tab/arrows to cycle
forward 5 widgets vs. going backward. This type of thing
will cause a Windows user to laugh out loud and tell you to
get a real OS.
Most people did never see that you can use Windows completely
without a mouse.
I once have been on a machine withour a mouse and I could do
everything with key shortcuts.
Best regards
ce