Citizen Kane was a masterpiece ... up until that point.

Every decade and every generation does something better than the last, and it makes an impression on audiences in that era. Those people carry that experience with them and, one decade after the next, that "masterpiece" gets carried over into the "cultural canon" of great films.

"The Birth of a Nation" is widely considered the first Hollywood "blockbuster" film, but you'd be hard pressed to find almost anyone today to sit through a 3-hour silent film. It's the same with athletes. The guys from the 40's and 50's are legends, but there's no way they'd keep up with the microdosing, hyper-metabolized athletes of today. And yet, we still think of guys like Babe Ruth and Aaron Judge as somehow being on the same level. It's really not a fair comparison; they're each legends in their own time, in their own way.