It’s hard to see why any Harry Potter theory would rile up the fans so much, especially when looking at this one it’s really more of an ‘aha’ moment than anything since when one looks at the Chamber of Secrets and the dark mark that the Death Eaters carried on their forearms it makes a lot of sense. how Tom Riddle ever managed to get away with half of the stuff he did is the real mystery, but the image of the basilisk coming from the statue of Salazar Slytherin’s mouth and being translated into a serpent coming from the mouth of a skull sounds pretty straightforward to a lot of people once they’re given the connection that Slytherin’s green color and their affinity for snakes is a huge sign. Plus, the whole parseltongue thing that Riddle and others of Slytherin might have shared is another great way to use the imagery since the act of speaking to snakes was something that one might expect of Slytherin. It sounds fair to say that a lot of fans weren’t really expecting the main character of the story to be able to talk to snakes when it finally came, especially since snakes were the animal that belonged to the house that he was most opposed to. But the fact that Harry spoke a snake in the zoo was evidence enough, though no one knew it at that time since no one apart from those that had read the books knew what parseltongue even was.
But after seeing the dark mark it probably should have been kind of obvious that things were going this way, no matter if this theory has yet to be fully accepted by everyone, which is odd really. Why anyone would fight this kind of a theory, which is about as common sense as it can get, is hard to say. But the idea of the dark mark originating from something that Thomas Riddle saw and enjoyed as an image isn’t too hard, but thinking that he meant to have a magical tattoo given to his followers is something different that is kind of odd within the wizarding world since tattoos aren’t something that were really given a lot of attention until it came to the dark mark. Granted, being a kid’s movie to start with it wasn’t bound to be something that would come up since it might have made some parents a bit apprehensive, but body markings and fantasy are actually quite intertwined, so perhaps Rowling finally realized that adding in something along this line would be a good idea just to keep things advancing in a manner that would hook in more viewers.
Now that it’s been revealed though it does feel kind of like a huge ‘duh’ moment since the imagery was right there for so many to see, but the only excuse, which is a good one really, is that there was so much going on in the movies that it was hard to notice this at first. There are likely a few people out there that noticed this said ‘cool’ and moved on, but years after the movies ended, people are still finding new theories and ways to enjoy the movies and the books that a lot of people might not care about or might be intrigued to hear depending on how much they enjoyed the story. In all honesty, some people simply enjoyed the movies and didn’t want to go any deeper with them, while some folks read the books, then watched the movies, and were somehow disappointed. It’s true that the movies left out quite a bit of information that was in each book, but when trying to explain this to folks many still don’t want to understand that filming a book exactly as it’s written wouldn’t be possible with time restraints and because it probably wouldn’t come out in the manner that people wanted. The idea that a book can be filmed entirely as it’s written isn’t impossible, but it’s definitely not something that many directors are about to do without altering a few things simply because there are moments in novels that don’t translate well to the big screen.
Harry Potter is a story that played out well on the big screen but also had to be altered just enough in order to get people to really understand and enjoy the story in a manner that could be shared worldwide. From the first book to the last there was a lot of material that was changed and a lot that was left out. But the point is that even the people that read the book enjoyed it since they were all about the story and found it to be pleasing no matter what happened. But yes, the dark mark theory should have been easy to spot.