Does not mean based on a true story
It is all in the wording "based." I cannot be certain of this, but I believe it says that it was based on "Actual" events, which is not the same as "based on True story." One of the better "documented" or believable haunting s is The Bell Witch, which was actually believed to have been an invasion and a death was actually attributed as well.
The Amityville was a big hoax and even Margot Kidder said that it was one of the biggest mistakes she ever made and didn't believe the story at all. I think the Lutz's or whoever may have gotten sued.
"The Texas Chainsaw Massacre" was based on an actual person and not on a true story, even though I have actually met people that swear that they remember it taking place.
This story could be based on actual events that occurred in a lot of different places and just put up in one story like "Dead Man Walking." The book was about a couple of different murders though the actual people are real. This could be the similar situation. I do believe in the paranormal state and unexplained things that happen, the metaphysical. I just do not believe that humans have developed a science to confirm it. I lived in a place that was "haunted" but nothing bad happened, just some things disappearing and showing up some where's else, a child humming, the sound of some one closing a door and walking up the stairs (which happened when me and one of my housemates were together) and yet no one came in or out of the house. All of us experienced these things sometimes together or some times alone. It was strange, but not bad, though when I first moved in a got a very negative feeling in my stomach and burned white sage and then it went away. I can't explain it, but it happened.
Besides, sometimes a good haunting or "ghost story" is just fun to watch whether based on actual events or not. I do not know if it is a hoax or it there was a particular family who experienced these things, but I would be skeptical especially since "Amityville" came out and the Lutz's conned a lot of people.