Lead sections shouldn't require citations, per [[WP:LEAD}]. Any important information must be sourced in the article body. Sort out the article body first, then figure out what to do with the lead. Also, you shouldn't have to sort something five times. If you're citing something five times, it's either overkill or you're really trying to push something. 

 As for the whole debate about hard rock and metal: metal has been extensively studied and written about to the point where it's very well-defined, while hard rock has historically been treated more as a broad term that applies to any sort of aggreesive rock (not only metal, but punk annd certain prog and alt-rock artists). I also think it's funny that one of the sources used in this lead example is Allmusic, which also goes on elsewhere on its site about how important Zeppelin is to metal. Just some things to think about.