Why are people even saying it's a port? Was it not confirmed a new game officially?
People say it out of habit. It's a common thing that a Nintendo game gets wrongly accused of being a port. The people who say it fall into two different categories:
1. Disgruntled Nintendo fans who use extreme hyperbole because they are disappointed for whatever reason. Said reason doesn't even have to do with the game itself.
2. Detractors who are either scared or jealous, but would never admit it.