When people say things like "intelligence doesn't exist" or "race doesn't exist", charitably, they don't mean that the folk concepts of "intelligence" or "race" are utterly meaningless. I'd bet they still use the words, or synonyms for it, in informal contexts, analogously to how we use informally "strength". (E.g. "He's very smart"; "They are an interrracial couple"; "She's stronger than she looks"). What they object to is to treating them as a scientifically precise concepts that denote intrinsic, context-independent characteristics. I agree with gjm that your parody arguments against "strength" seem at least superficially plausible if read in the same way than the opponents of "race" and "intelligence" intend theirs.