Because at it’s heart, JFK is an old-fashioned detective story. A classic whodunit with somewhat higher stakes. This isn't a fictional work about a fictional wrongful death; this is a version of history. And as much as he's trying to tell a story, Stone - like his protagonist, Jim Garrison - is trying to make a case to the moviegoing audience.
This movie came out when I was a junior in high school and taking A.P. American History. My teacher would not. stop. talking about this film in the weeks before and after its release, and lambasted it to Glory and back before he ever even saw it. Lots of historians did that, as I recall. I remember thinking at the time, Why don’t they just SEE it before deciding how bad it is? Of course, the history buffs who did see it occasionally blasted it even more ferociously. There are all kinds of articles and websites devoted to the historical inaccuracies of the film. This one lists 100 of the “most egregious errors” in the film, and presumably there are many more, according to historians.
Of course, the trouble with history is that it is written by human beings who are just as capable of error, misjudgment, and plain old bias as Oliver Stone might be. But make as many lists as you like about how much of it is or isn't factual. Even if Stone's version, or Garrison's for that matter, isn't 100% legit, they both make a rather compelling argument. There is no way that Lee Harvey Oswald acted alone.
This movie crystallizes a time in our nation's history when innocence was lost. From the assassination of President Kennedy to the allegations of conspiracy to the King assassination and finally the assassination of Robert Kennedy - the latter two tragedies happening within a mere few months of one another - were part of a turning point for our country, and the decade to come would be marked with a profound cynicism about not just politics but the world at large and the big, important words that we tend to capitalize, like Truth, Justice, and
The centerpiece of this film, of course, is the shooting itself. We see the shooting several times, and each time we see it, we observe it in a different way, with a little more insight each time. Until we finally see the shooting for the last time, in one of the more staggering examples of editing-room genius that I have ever seen, where Stone uses the Zapruder film and cuts into it with all kinds of archival footage, as well as Stone's own shots of his actors in the key roles. This is a few minutes of the film's running time, but it takes the previous three hours to get us ready for that. And if, indeed, there was a conspiracy, it was a brilliant one, because it's nigh impossible to put all the elements together and figure out exactly what happened. We may never know how many people might have been involved in the events of that day.
I think it's pretty awesome that the popularity of this film actually led to a legislative act (The President John F. Kennedy Assassination Records Collection Act of 1992) and the formation of the U.S. Assassination Records Review Board. The government also decided to make some of the classified documents related to the assassination open to the public and moved up the date when the public will have access to everything else the government has on the assassination - from 2029 to 2017. Talk about the power of film - Garrison would have been proud. Sadly, he died five days before Congress passed the legislation.
Fun stuff: Kevin Costner, who starred in this film as Jim Garrison, was in another movie four years previously called Bull Durham, where his character, Crash Davis, takes a position on the JFK shooting that is as opposite as can be from Jim Garrison's. Anyone remember? It's in that awesome speech near the beginning (the "long, slow, deep, soft, wet kisses" one). Right between Susan Sontag and the designated hitter, he says "I believe Lee Harvey Oswald acted alone." Okay, well, I find it funny. :P
I leave you with movie!Garrison's explanation of the Magic Bullet theory.
BONUS: Just for kicks and giggles, here's a GENIUS parody of the above scene, courtesy of Seinfeld. How awesome is it that Wayne Knight is in both scenes - IN THE SAME POSITION!