It is a common mistake to think that etymology is relevant to defining the meaning of words. Mutualists take note.

Yes, I think libertarians should in general avoid using the term “capitalism” in reference to a free market or all voluntary human interaction (or outside macro-economic discussion, anyway) because it is confusing. I have said as much here before. However capitalism is a much less broken word than anarchy. It has a much less bad reputation. It has a useful, standard technical definition in modern economics. And avoiding the word does not mean it makes sense to call oneself an “anti-capitalist” any more than I think libertarians should go around calling themselves “anti-anarchists.”