I always knee-jerk about this kind of discussion, because trying to be stringent about genres and "what is a real X" inevitably leads to to the obnoxious "X ISN'T A REAL VIDEO GAME" whiners that populate much of the internet. So I've no great opinion on this.

Other than to say that Horizon: Zero Dawn is absolutely not an RPG. That's the only allowance I'll make of those three quibbles. That's it.