Bob - you wouldn't want to do it - play in basic set-up, that is - but it's a useful way for beginners to get into producing a reasonable version of a song quickly as most beginners struggle to find their 3 finger chords let alone those that need four fingers.
Many's the time I have listened to junior players hanging on the melody note way past the four beats of the bar whilst their memory hunts for the chord for the left hand...and it must be frustrating for them too...and that is probably why lots of expensive keyboards end up in the loft or under the bed!!!