There's actually RPGs of every type of material in japan. The saturn has some strategy RPGs that were about football (soccer). I actually wish there was a translation for it, I'd really like to play it.
I would argue there's a difference between a game being an RPG and having RPG elements. I don't think anyone would argue that Modern Warfare 3 is an RPG ... but there is indeed a persistent stat system unique to the player (not the character).
I think, honestly, the genre of RPG is only the official genre of a game if that's the primary style of play. So, if the game is molded around RPGing, then it's an RPG ... if it's not ... then maybe it just has elements.
For example, Mario Tennis does have persistent stats in some of them ... but the primary gameplay is not character building of any kind, it's playing tennis and tennis mini-games. So, I would argue it has RPG elements, at best.
To be honest, the entire argument of genres is misleading ... because a lot of genres are defined subjectively. And you can argue elements of many genres in any give game for various reasons. I think a better system all together is something more like a tag system. Not that they work so well when people aren't accurate ... but if you described basic genre elements that existed in a game with a weight (how proficient the game is in using those elements and how important they are) then you'd get a much more defined look at how games would be classified (and maybe even have a better rubric for choosing new games to play) Then you could be very specific about what each tag means and you don't have the mess of sub-genres.
You can make that kind of system as complex as you like, too, so separate tags for individual aspects of a game, for instance. This of course, doesn't help anyone here
It's just something I've personally mused over when thinking about building game collection systems and databases.
