The Marvel Cinematic Universe is the king of the cinema today. The franchise has taken the interconnected continuity of the comic book and applied it to film in a way that nobody had ever tried before, and has found success that even Marvel probably wasn't expecting. However, Kevin Feige says that another major inspiration for the MCU was actually the Harry Potter movies.
Specifically, Feige told the New York Film Academy in December that it was his experience watching the films, and not reading the books, because he's never actually read the books. Feige says the films worked simply because they didn't require the audience to have read the books, though they likely gave the audience that did additional value, and he tries to do the same thing with the MCU. According to Feige...
I always default to my experience watching Harry Potter movies. I went to see every Harry Potter movie opening weekend. I saw it and I enjoyed it and then I forgot all about it and didn’t think about it again until the next Harry Potter movie came out. And those movies were so well made because I could follow it all. I could follow it, I could track it, occasionally I have to go, ‘Who was that?,’ but for the most part I could totally track it. Now if I had watched every movie ten times, if I had read every book, I bet there are dozens of other things in there that I would see and appreciate, but they never got in the way of me just experiencing it as a pure story. So that’s kind of what we try to navigate. If an Easter egg or a reference or something is so prevalent that it gets in the way of the story you’re telling so that people who aren’t aware of it go, ‘What is this? What’s happening?,’ then we usually pull back on it.
Kevin Feige was responding to a question asking how decisions were made trying to balance MCU movies for both the serious fan and the casual moviegoer. Feige admits that trying to please everybody is impossible but he points to Marvel's use of test audiences as a sign of the success they have had. Apparently, test audiences that see early cuts of Marvel films, who have never seen a Marvel movie before before, largely feel that prior knowledge isn't necessary. The references that are there don't get in the way of a new fan's enjoyment.
The Harry Potter books, especially the later ones, were immense novels, and as such a lot of material had to be cut out and rearranged. Of course, you only knew that if you had read them. Those that had read the books, knew a lot more about characters and interactions and details that weren't in the films, but the movies each stood on their own. No additional details were needed to make sense of the story.
And this has been the secret weapon of the MCU. There's this sort of general feeling that one needs to see every movie in order to understand the larger story, and that helps the box office of each and every Marvel movie. But the reality is that most of the time the connections that are made are inconsequential to the movie that you're watching. If you miss them entirely, it doesn't actually matter.
I for one can speak to the success that the MCU has in this regard. My own wife has watched all the Marvel movies with me, most of them only once, and she usually enjoys them, but has also said that she pretty easily forgets about them once they're over. Then the cycle repeats with the next movie. Her experience watching the MCU follows closely with how Kevin Feige watched the Harry Potter movies, so apparently this strategy has been working quite well. She's always interested in seeing the next MCU movie, even if she can't really remember what happened in the last one. But it largely doesn't matter.
Fans of the MCU want to go see every movie in order to follow all the connections and try to figure out what's going to happen next, but Marvel Studios understands that catering exclusively to that audience isn't enough. There are a lot more people who might only see a few of these movies, and either way, the movies need to work on their own, not simply as pieces of a larger puzzle.
Kevin Feige does admit that movies like Avengers: Infinity War and Endgame are a bit more difficult to handle this way than other films. Now that those movies are over, we can expect that Marvel will be going back to a model that is more designed to appeal to both the familiar and the new.
Marvel's Phase 4 will include new adventures for familiar heroes like Black Widow, Spider-Man, Doctor Strange, and Thor, but it will also introduce entirely new characters like The Eternals, and Shang-Chi. While these characters will probably have their share of connections to the existing MCU, they will also certainly work as standalone movies designed to bring in a new audience that maybe has never given the MCU a chance before.
As far as the Harry Potter films go, the Wizarding World franchise appears to have gone in a different direction. The Fantastic Beasts movies seem to be more dependent on the audience knowing more about the world than what has been specifically in those movies. It's even been said that the future movies will connect even more to the original films.
Whatever the reason, it's pretty hard to argue with the success of the Marvel Cinematic Universe. Avengers: Endgame is the highest grossing movie in the history of ever. Following more than 10 years of success, the MCU has two years of movies and Disney+ series planned for the future that we know about, and even more after that which we can expect.
Will there be a point at which the MCU becomes too big and the references and connections become too confusing? At this point, that certainly seems unlikely.