those that use audio loops, arpegiatos, lipsyncing cheat also.
of coarse Arranger keyboard gives users more apportunity to cheat, especially with the Intro, Ending buttons, preprogrammed 'Styles' 2 finger chord recognition and the whole Auto-Accompaniment thing !

You also can use Arranger-keyboard for fair, non-cheating stuff like:
Producing Songs (from sratch), playing live(without using styles)