That's because
The Simpsons is far more well known for three decades and is still ongoing whereas Nat Geo (where it deals with
nature, science, culture, and history) and Disney Original shows are not. Disney originals has like a couple of good shows, and the rest is just behind the scenes of documentaries about theme parks. Still, the Simpsons is the least valued in the chart when compared to other entertainment contents on the service like MCU, Star Wars, and Pixar, since
The Simpsons has yet to fully assimilate into Disney's core identity, is a story only about them, and is almost three decades old (where most people who grew up in the 90s and 00s are already grew tired of the show by now).