Who is F. Scott and Zelda Fitzgerald from Hollywood: A Novel and what is their importance?

F. Scott Fitzgerald was a famous novelist who, equally famously, was a spectacular failure at screenwriting. Zelda was his wife who, just as famously, went insane. Both Scott and Zelda were heavy drinkers and hard partiers, an evident parallel to the lives and experiences of the hard drinking (but somewhat less hard partying) Hank and Sarah. On another level, it seems to the reader Fitzgerald's failure is something Chinaski fears.