Talon4, as Viridian mentioned, ALL of the groups that you mentioned from the 1970's released albums in the late 1960's. They did, however, come into mega-star status in the early 1970's, with some of their best selling albums (as well as their most creative and artistic works [IMHO]) between 1970 to 1975.
The majic of early 1970's rock and it's influence-
Starting with the Beatles and the Rolling Stones in the sixties; then adding in the Vietnam War, and the sexual revolution, which also occurred at this time, I think the time frame of 1970-1975 created the majority of rock's geniuses, the likes of which probably won't be seen again. I use, for examples- Jimmy Hendrix, Pink Floyd, Yes, Elton John, Genesis, the Allman Brothers, Janis Joplin, Eric Clapton, Jethro Tull, Santana, and Neil Young, just to name a few. I think earlier (pre 1970) rock concerts of large attendance, such as the Beatles tours and Woodstock also had a profound influence on the social change during this time. What do you think?