Well, yes and no. I oft times play the melody to lead in a singer and on parts I know the singer will have difficulty with. If they tend to stretch to certain notes or sing off-key, I play the melody OR I incorporate the melody into my block chords to help the minds eye of the listeners resolve the singer to "On key". There are instances where I do play along with the singer for songs like, Spanish Harlem, which begs for a sort of "Duet" sort of sound.

I don't think it hurts to help singers along once in a while! :-)

Al