Well, my point is just that, there were better bands than Led Zeppelin doing blues, jazz, doo-wop and every other genre Led Zeppelin had no business (in my opinion) doing. Maybe they didn't listen to enough records and pilfer enough material to come out with all-rocker albums.
Early thin lizzy just isn't what I was expecting. I recall watching a concert by them from the second or third albums tour and thought it was good, but then listened to those albums and it just didn't do it for me. I like songs that are big country-esque like black rose and angel from the coast myself.