So, you're saying people can just learn an element or what? This is why I don't get it. If people have certain affinities for elements, that should be the only element they are able to use. Why would Kakashi's affinity be only lightning, and still be able to use two other elements, but is unable to use another two? Is he not compatible with wind and fire, but is compatible with water and earth? Does this not mean these elements are also his affinity if that was the case?
It's not necessarily a massive assumption. I based it off of your thread which said Naruto got Yang from Kurama's chakra.
I mentioned it in case you might say something along the lines of, "Even if he had Mokuton, he wouldn't be able to use it right away."