I think it is a case of: Do you know a better way of measuring intellectual attainment?
There are many types of intelligence, and intelligence tests to do not claim to measure every type, just intellectual levels.
Yes, like any test you can get better with a bit of practice, but again it is not a question of saying at this score you are this, and at the other score you are precisely this much brighter,
I note that it always the intelligence test that everyone gets screwed up about, no one queries when someone shows high attainment in sport, or when we taalk about emotional intelligence.
I think there is something very deep and primal in most people that really resents knowing that someone, or worse someone elses child has an above average intelligence - an intelligence higher than theirs or their childs.
We all recognise when someone in the public eye is highly intelligent - Professor Stephen Hawking, Professor Brian Cox, Stephen Fry, we just do not like to admit it if there is someone in our world is obviously more intelligent than most.