I think it works better with BtVS magic, though, since I think in Jossverse, most people can learn to do at least a little magic, though some people are naturally much better at it than others. And it seems to me that most people in Naruto can learn to use chakra, if they're willing to put in the time and effort, and can find someone to teach them -- otherwise, I think the classes in the ninja academy would be much smaller.

I may be way offbase, but that's the impression I get from the manga. (Also, it goes along with the sort of 'equalization' of martial arts, and with Lee's example, where effort can make up -- somewhat -- for a lack of natural talent.)