In the silent era of cream pies and pratfalls, many of their more acrobatic peers from vaudeville made it in Hollywood, while the Marxes stayed in the theater. But when sound arrived, so did they. The complicated causes for the rise of a successful popular entertainer are a tangle best apprehended by the micro-surgical tools of biography. That's why Stefan Kanfer's biography of Groucho is a good one, and why it would have been better if it had avoided the superimposition of unconvincing reductionist drivel on its marvelous backstage saga. Social forces don't kill audiences.
Good comedians do.