"Obviously it can get to the point where it gets past being a compliment, and it can be rather annoying, when you've got things like Kingdom Come, actually ripping riffs right off, that's a different thing altogether."
My cousin left a Kingdom Come tape at my house. I'd never heard 'hard rock' music before I listened to it and I thought it was awesome. I even took up the guitar so I could learn to play 'Living Out Of Touch.' After that I never cared much for Led Zep.
When I heard the original blues/celtic folk songs Zeppelin ripped off, I preferred the Zeppelin versions. So the cycle continues, wheels within wheels man.
Actually it is kinda karmicly just for bands to totally rip off Zeppelin songs and riffs without providing credit. Jimmy Page found out how Willie Dixon felt about The Lemon Song.