tspikes51, Led Zeppelin is not overrated.
There's just no way. Their style is exponentially beyond just "rock".. the foundation of their music is based on SO many different styles of music, it's not even funny.
There aren't very many artists that have used as much diversity in their music as Zeppelin. Well, no, some do, but they aren't very good at it. They aren't able to take each individual style and morph it into something unique and original. It's usually a blend of "here's a Zulu Tribal beat on top of some 80's German industrial". It's not a "I am well knowledgable and trained in the foundations of folk/blues/r&b/etc.. and I wanna take these and make it into a style that has never before been heard."
To prove the point, they're still relevant today. Their status is legendary and their place (and importance) in music history is equally as legendary... based on that alone, they can't be overrated. I said this in another thread, but you can personally dislike them all you want, but to say they're overrated is a gross misjudgement on your part.
I guarantee you that every modern band you enjoy has been influenced by Zeppelin in some way.
You got it all wrong though... you can't "master" music. Style exist to simply try and categorize the music that people create to express what they need to create. Some create truly unique and original music while others take what has already been established and simply build upon that. You can be good and proficient at that style, yes, but master? Not so much.
Garth Brooks (?) hasn't (and isn't) proficient in anything rock. I'm not a fan of country at all, so I won't comment beyond that. Beck mastering rap and rock? Eh... not really. He's awesome, yes, but he's not ROCK and most certainly isn't RAP. He's experimental. Smash Mouth? Hahaha... did you throw that in there for laughs? They haven't really mastered anything except how to sell well in the bubble-gum pop world. A prime example of a band that wont' be remembered 20 years from now
The music you hear today was essentially created by Zeppelin (amongst others, like Sabbath and the Beatles). You simply can't discredit that as "overrated".