What is the re-play value of comedy albums?
For adults in the 70s, by which I mean my parents, I think it was the equivalent of owning a Seinfeld DVD box set. They had favorite moments from each album and it was something to share and laugh at when friends came over. It was after all one of the few in-home on-demand entertainment options at the time. For me, though, the George Carlin routines were like nursery rhymes. They had fun words that I didn't completely understand but wanted to hear over and over. I can recite them to this day.
But maybe my experience is not typical.