So is this article going past strict game mechanics and noodling over to the narrative elements, then?
Narrative genres are a whole mess of blurry sometimes.
Though if you were to take a purely narrative look at it, choice and dynamic story options (maybe even just alternate endings, since we're only looking at Zelda here) are what define an RPG. I look at games like a stage play. The majority of games have a script, your director is a snob, and you had better get your lines right.
The best RPGs are improv. You have an idea of what is wanted, but otherwise, have at!
EDIT: Which reminds me of some tabletop RPGs that don't muck about primarily with stats and focus on dynamic group storytelling. A lot of homebrew tabletop RPGs are like this (and I don't blame them) as well as the majority of LARPs.