Well, only if you believe that the inability to define a term entirely without ambiguity renders the term unintelligible and useless.
Most people do not believe that.
For example, there is no “consensus” about the term “person” (Is an embryo a person? Is a brain-dead human a person?) but the occasional ambiguity doesn’t prevent us from using and understanding the term in everyday situations. We can all agree that Hillary Clinton is a person, I imagine. We don’t have to throw up our hands in despair in a clear-cut case simply because “experts” might not agree in the rare, ambiguous ones, do we?
So, thought experiment–suppose we pull 50 wealthy, native-English-speaking 17-year-olds with 2350+ SAT scores out of high-end New England boarding schools and put them on one side of a soccer field. Now suppose we take 50 wealthy, native-English-speaking 17-year-olds with sub-1600 SAT scores out of similar schools and put them on the other side of the soccer field. Are we really not able to agree that most of the kids on the 2350+ side of the field are just plain more intelligent than most of the kids on the sub-1600 side of the field?