When I was growing up, there was a really strange time, it felt like it lasted like 20 years, where every single Best Album Of All Time list had "Sgt. Pepper's Lonely Hearts Club Band" at the very top of the list. And... I could not understand it. it's not even the best album _by the Beatles_.
It wasn't until I got into my mid-thirties, that I realized, oh: 1967. Right.
It's not about Sgt. Pepper, it's about the nostalgic memory of being eighteen and high while listening to Sgt Pepper.