Think about some of the most common tropes in horror movies. You've got gore, sex, and all that fun stuff, but there is one trope that seems to be exploited.
The idea of a movie being "based on a true story" or "based on true events" is becoming a cop-out. It has become more and more of a marketing gimmick as time ticks forward for the simple fact that it puts asses in seats. People want to see a dramatized version of the events that took place. But most of the time, it's so dramatic the movie loses sight of the more important aspects. I've chosen two prime examples of this as well as smaller examples I'll touch on in a bit.
'The Amityville Horror'
The first thing that most likely comes to mind when you hear that are the haunting things the Lutz family claimed to have dealt with. (I say claimed because with a small bit of digging you find out quickly the story was exaggerated from the beginning.) Aside from that though, not many think about what happened the morning of November 13, 1974. It was that morning when Ronnie DeFeo killed everyone in his family for seemingly no reason aside from the extremely toxic relationship with his father. But the movies don't talk about that. The story of the DeFeo family is often relegated to nothing more than an opening scene to set the stage for the "more interesting" story. That being of the Lutz family.
And of course, we can also touch on what the movie says about Ronnie as a person. For clarity sake, I'm talking about the 2005 film. In that film, it is said multiple times that Ronnie murdered his family because he heard voices inside his head telling him to kill them. That's where the whole "Ketchem, Kill'em" plotline came from. They also mentioned something about the house being built on an ancient burial ground. That part I'm not so sure of, honestly. The real thing that needs to be addressed here is that Ronnie was not schizophrenic and didn't suffer the delusions that the movies would lead you to believe. That entire idea was brought up by his defense attorney during his trial and was eventually thrown out. While Ronnie DeFeo did suffer from certain mental disorders, he did not hear voices.
Ronnie's story is the one that should be told.
Six people had their lives taken that night, and they're being forgotten more and more every time a shitty, money grabbing remake is released.
'The Texas Chainsaw Massacre'
This one is a bit of a different case for one reason; only parts of the real story were used in the film. Still, though, we see the same problem arising again. Ed Gein was the main inspiration for the character of Leatherface; I believe we all know that. But, when the movie is marketed as being "inspired by a true story" it again, puts asses in seats. So, let's take a look at Leatherface and see if he parallels Ed in any way.
Leatherface is a mentally disabled man driven to kill by those who take care of him. He knows no better seeing as that's what he's been taught to do. Ed, on the other hand, while believed to have had some type of disorder (like antisocial disorder or possibly Asperger's syndrome), he was treated fairly well as a child. He was never told that killing was what he was meant to do. Of course, as he got older and his mother passed away, things took a turn for the worse.
Despite what many people believe, Ed Gein was not a serial killer. He only murdered two individuals through his life, possibly three. (That is his brother although it was never proven.) "But what about the face mask and the lampshade of human skin?" I hear you saying. Well, those were all created by stealing bodies from a local cemetery. Ed was a groundsman there for quite some time, so he had easy access. What the police found when they entered his home, however, is what Hollywood was interested in.
They took the part of the story that was most shocking and ran with it, creating a character that only barely resembles a shred of Ed Gein. The same thing took place with Buffalo Bill who was also based on Ed Gein. Again though, we're seeing the real story being watered down and ultimately forgotten. A majority of people believe Ed Gein to be a serial killer and latch onto that rather than remembering the people who were removed from their graves or had their lives taken for Ed's amusement.
Maybe I'm looking far too deep into this but I personally feel that these movies that are "based on" or "inspired by" true events are doing nothing good for society as a whole. It sounds extreme, really, but when we forget the real story and only remember what's been presented to us as "based on fact" we forget the importance of the real story that started it all.