By that definition you would have to completely discount many many JRPGS, such as Eternal Sonata and Final Fantasy X. An RPG is exactly like it says in the title. A Role Playing Game. Having a character and building up said character. So long as you have that, it counts, so no, I can't see where you draw the line because I disagree with youdon't the latest Call of Duties and Battlefield's have skill up's also? granted this brings up a good point, what components are needed for a game to be an RPG?
It certainly requires more than being able to add talent points to certain skill sets. To which we segue into...
Ohhh ohhh lets not forget Bioshock!
Love it, but completely linear, no quests, no ability to create a character. You can modify your abilities with talent points, and that's it. Doesn't count as a FPS/RPG hybrid IMO. Emphasis on a coherent plot does not make an RPG either.
I'd say an RPG requires a set of quests to be completed, some mandatory, others not. NPCs to interact with (talk, give quests, buy/sell/trade). There should be a rather in-depth inventory and skill system; the ability to either configure a party or personalize a character. Most of them have open world exploration of some type (like Final Fantasy and Mass Effect and Fallout 3).
They've already been used as examples, but hold Fallout 3 or Mass Effect (best FPS/RPG hybrids) up to Halo 3, CoD4 and Bioshock (premier FPSs of this past gen) and you can pretty clearly see where we can draw the line.
Fine, CoD4 was last year's most popular RPG.
Your logic claims that a whale is a fish because it swims underwater, and a Ford Explorer is a sports car because it has four wheels and can hit 60 mph faster than a Mazda MX-5.
If "playing a role" is all it takes to be a RPG, then almost EVERY game is an RPG. You play "roles" in all of them!