One day if we'll have the explicit formula for human Coherent Extrapolated Volition, it may become possible to measure one's impact on the society on a single scale. Until then, there is no such thing as a scalar "a.impactOnSociety(time)".

Also: there are many sources of evidence about a person. Some people stop immediately after taking one piece of evidence (such as race) into account, even if there are other pieces available. Of course such motivated thinking is a mistake separate from mere "using evidence about people / groups".