Oh, come on. Led Zeppelin do not beat The Who in musical impact. Especially since it's defined primarily as reaction to your work soon after its release.
Yes, they do.
No, they do not. Nothing in Led Zeppelin's repertoire had the impact of "My Generation", Tommy
or Live At Leeds
. Arguably not even the impact of Who's Next
. The Who's praise is beyond Led Zeppelin's.
Led Zeppelin were also as reviled
as they were praised in their day: "Just looking at their album covers makes me want to throw up." - Paul Simonon
Even today you have opinions like this: "Fuck off, Zeppelin, you're crap. You've always been crap and you'll never be anything else." - Jack Bruce
But here's John Lennon talking about Yoko Ono:
"I’m digressing from mine, but if somebody with a rock-oriented mind could possibly hear her stuff, you’ll see what she’s doing. It’s fantastic, you know. It’s as important as anything we ever did, and it is as important as anything the Stones or Townshend ever did." link
That shows you what enormously high regard John Lennon held The Who in. When trying to come up with the most important work in rock, he's got an awfully short list. I think it would have been a long time before he got to Led Zeppelin.