So, I do love insane fan theories having to do with movies or shows I grew up with. One of my favorites, for instance, is the theory positing that My Neighbor Totoro is actually a story about the two protagonists meeting a Shinigami, otherwise known as a god of death. Granted, it later tried to tie in an actual murder case on top of that with...believability lessened due to obviously fabricated evidence (one of the sisters saying she saw a cat monster and large Japanese raccoon dog before killing herself is one). But the one that I heard since high school was the Rugrats Theory.
I used to actually really like the story. I mean, obviously, I knew there actually was no dark secret behind The Rugrats, and it was just a story. The notion of Angelica actually being a real girl is what cheapened the experience for me. The story itself where it suggests that Angelica imagined all of the babies up and each one died in different circumstances such as stillbirth or vehicular accidents is thought-provoking with the opening sentence being an eye-opener.
But at the same time, where the story falls short is that it's just the generic "every character is dead" cliche prominent in several theories speculated for cartoons. It's one of the laziest plot devices that there is along with stating that the character is in a coma imagining everything and never waking from it. It might've been original at that time since it probably predates other "Creepypasta" that has a similar plot device like Ash's Coma or "Cul-de-sac," but that means it didn't age well. In fact, it may as well be the progenitor of them.
The story also came off as shocking just for the sake of being edgy. So you have a story about the titular Rugrats not being real and just the imaginations of Angelica Pickles. Great. How did each one die? Stillbirth. Okay, it's shocking, but I can let that slide. A car accident? It's fine...even though in the actual show, Chuckie's mom was sick and she died from her illness. The twins were aborted? It's not so much that I'm offended by the concept. It's more the fact that it was added in without much substance behind it other than "Well, this happened. Be disturbed." Sure the point of the story isn't the deaths of the children, it's Angelica imagining them. But I never really understood that aspect. Yeah, Angelica was an only child who had a busy mother and neglected in the context of the story, but why create dead babies as your imaginary friends?
And then as if the story needed to have more edge, Angelica bashes Dil in the head when she was mad he didn't disappear like the other babies which gave him a brain hemorrhage, and she started to take drugs because she felt guilty for screwing his life over. So you have that combined with drug abuse, prostitution, addiction...the list goes on.
Overall, not one of my favorite "theorypastas" because I feel that it started the trend of using dreams, purgatory, mental illnesses and the like as "explanations" behind why a show is the way it is. It uses touchy subject matter as abortion or drug addiction so loosely while at the same time trying to tie a weak story around to justify it. I do like the Vocaloid song that is based on the theory, though. That was genuinely good.