Yes, we have all heard of Led Zeppelin. That is not my point -- my point is that I've seen roughly one million "Music from 1968/1969 is The Best!!!!111" articles / essays / etc in my life, and zero "Music from the 1970's changed the World!" articles, even though Led Zeppelin 4, Joni Mitchell's Blue, Songs in the Key of Life, Fleetwood Mac's Rumours, and a bunch of other amazing stuff all came out then.