The writer's argument depends most upon the reader's accepting that
(1) the Beatles had eight of the nation's top ten songs in 1964
(2)
Brian Epstein created the Beatles
(3)
"long hair" image
Berry, Holly, and Presley were the leaders of rock and roll before the Beatles
(4)
Brian Epstein got the Beatles their first contract
Brian Epstein died in the late sixties
(2) Brian Epstein created the Beatles.
This statement is crucial to the writer's argument because it establishes Epstein's role in the success and management of the Beatles. If the reader does not accept this premise, then the rest of the argument about Epstein's influence on the Beatles' success may not hold as much weight.