I don't get it, you guys just keep quoting a small part of an entire article? The whole RPG-systems article goes on and on about the different kinds of rules and stats. Your very own quote even speaks against you:
"A role-playing game system is a set of game mechanics used in a role-playing game (RPG) to determine the outcome of a character's in-game actions. While early role-playing games relied heavily on either group consensus or the judgement of a single player (the "Dungeon Master" or Game Master) or on randomizers such as dice, later generations of narrativist games allow role-playing to influence the creative input and output of the players, so both acting out roles and employing rules take part in shaping the outcome of the game."
It says both, not or, and the rest of the article is about stats. How do you explain this? How can you interpret this as "RPGs do not need stats" when all articles so far mention stats as an important element? Sure, narrative and creative input are important, but those still can't ignore stats, especially not in computer games.
And as far as I know, SS13 still tracks the player's health, so what you can and cannot do is not based purely on player acting, there are also restrictions based on pure numbers. And apparently you can select disabilities at the start, too, and alter stuff in-game with DNA or medicine. When a griefer selects a disability for himself, and decides to go OOC suddenly to ruin the game, will he lose his disability once he stops RP'ing it, or will the game still keep the effect? That's the rules and stats of the game working, making it a true RPG. Otherwise it'd just be an RP sandbox.
A lot of games are focused on playing a character and following a plot. Was Zork an RPG? Is Zelda an RPG? Is Tomb Raider an RPG? All these have you follow a plotline, and you can RP some extra character depth if you like, but they are not RPGs. They use player skill in order to succeed, while an RPG would employ player skill in managing the character's skills. A lot of the recent "fake" RPGs use levelling and stats to help the player kill stuff, still using player's skill at shooting and clicking. Like Fallout 3 and carp like that.
Playing a role, a character, is indeed role playing. It does not make any game a Role Playing Game, since that's a term for something bigger, which is ill-defined but does happen to mention the use of statistics in every single article so far, mentioning role play as what gives the games their flavor.