I understand that, and I have never argued otherwise. This is the reason I keep refuting the counter-arguments regarding other base number systems. We can divide things into thirds, we do it everyday! We can even divide into perceived equal thirds in base 10, we just assume the remainder. We have to assume it because we can't resolve it, as you just said. There is nothing real complicated about this, I am not making some bizarre outrageous claim, it is just a fact of the matter regarding 1/3 in base 10.
Fractional representations are not numeric values, they are division problems, which can be applied to values. You can add three 1/3's together and get 1, but you have added three division problems, all of which assume the remainder.