There are a lot of people who like FNAF, especially kids. There a lot of puzzles and alternate reality games that people have to solve in order to figure out the smallest details about the story. Even then, the details for the story are vague. With so little information it lets the fans' imaginations run wild. Lots of people jump to conclusions and try to make theories about the story.

There's a YouTuber named MattPat who makes videos about his theories for the franchise's story. He's pretty obsessed with it and has been a prominent figure within the community. His videos are entertaining but I personally find that he "leaves the planet" a little too much.

I suspect the franchise's creator decided to make some of his theories come true just to be nice. There's not a lot of doubt in my mind that the games were never meant to have a well thought out and complete story. There are books so maybe there's more information there. Though I don't particularly like nor care about FNAF that much so I don't really know. I just went to the movie with a friend who's really into it.