Because we as human beings have this unfortunate need to standardise everything with the help of numbers. We wrongly believe that we can judge the capacity and the capability of a person by their outer performance. This is however erroneous and slowly some leading educationists realise this. There are many factors that count for our real worth, most of which cannot be measured. But to understand all this mankind has to make much progress and it is far from that.
Affectionately,
Alok Da