Their churches may be small-c “catholic” in the sense of being universal, but this is not the same as being part of the Catholic Church (which is not only Roman, of course).
I may see myself as being orthodox in my orientation to my faith (in the sense that I try to not be a “cafeteria Catholic”), but if I go around calling myself an Orthodox Christian, I know many people who will have very big problems with that.
There is more to our affiliations than simply declaring ourselves to be X, Y, or Z. Part of being a large-C Catholic is recognizing the truth of the Catholic Church that is not wholly present in the Protestant churches. Why this bothers you, I don’t know. Surely if you are honest with yourself you must think that you have some truth in your own denomination that is not present in the Catholic Church, or else you would probably not be whatever type of non-Catholic Christian that you are.
So again, what is the point that you are making? That the Catholic Church is wrong for asserting about itself what you are in effect asserting about your own denomination, albeit in an indirect way?