Led Zeppelin album cover  

I hope I don't give anyone ideas.

Blues musicians have always used music and lyrics that were written by other artists. For instance Led Zeppelin got the line "squeeze my lemon" from a Robert Johnson song called Traveling Riverside Blues, but Robert Johnson had already 'stolen' a lot of lyrics in that song from a blues musician called Art McKay.

While Led Zeppelin did use a lot of music and lyrics that other people had written without giving credit, so did a lot of the original bluesmen. It's just that Led Zeppelin got rich doing so.

I agree that musicians always take lyrics and riffs - witness Blackmore's cheerful admission that the riff for Black Night is the base line of some obscure song, but to take the whole song from go to whoa and say that you wrote it is like me copying a Stephen King short story and putting my name on it. This wasn't a rewiring it was theft. The good thing of course was it made me check out guys like Willie Dixon and appreciate how good those early blues artists really were.

Don't get me wrong Zeppelin brought a lot of joy to a lot of people and were incredibly well managed to present themselves as the ultimate band, but there were many bands of that era who were more cutting edge and just as big then (Deep Purple certainly outsold them for several years) Where Zeppelin have lasted in the public mind is down to the expert management of John (?) Grant who stage managed (and still does) there every move - even down to the production of that album cover which the band would have had very little say in producing