This is an excerpt from the RatioIQvsDeviation IQ article:

Second, the �ratio IQ� may be more meaningful than a �deviation IQ� to families planning instruction. In selecting a textbook or a class it is more helpful to know that a seven-year-old is approximately four years beyond his or her age than to know that s/he is one in four hundred.

I agree! I look at those numbers such as 1/400 and think "but what does it mean IRL?" lol.