Hmm, worst singer and most overrated band?!  I'm assuming that in 1969 you must have been on LSD. Let me guess, you think "Stairway to Heaven" is terrible also.  Most bands do covers and take something from before them especially early in thier career. Its called the evolution of music. It goes back to Robert Johnson and the old blues men. Regardless of any "borrowing", I can't comprehend that you think Plant is the worst singer. Why not ask the hundreds of bands who have admited to being influenced by LZ. Longevity counts for a lot and LZ's music is still played regulary. So, what music have you produced lately?