Why do people say that Zelda is an rpg?

Ok, I have played almost all the games except for some of the newer ones and some handheld ones. Anyways I am wondering why people keep saying that it is an rpg. There are no "stat" Points, almost no powerups save for magic and health stuff. The only items in the game are those you get along the way. I mean, me personally, would clify the games under the action adventure genre, and somewhat of the puzzle genre because of the temples and stuff, but this is my own opinion, and I am wondering why they say it is. Please let me know why. I have contemplated this for a while and it just seemed to bug me more today than other days. Thank you.