An important step in the foundation of National Lampoon was a parody in the Harvard Lampoon called Bored of the Ring, which Tolkien signed off on. In a universe where the Beatles did an adaptation of the Lord of the Rings, the rights may be such that they never do that parody, meaning potentially no National Lampoon. No Lampoon, you've just butterflied away major elements of comedy, comedians' careers, Saturday Night Live (which ripped everything and everyone off or away from the Lampoon, back when SNL was funny and didn't play safe to midwestern tourists), major elements of the counterculture, and all the films that came from the National Lampoon.