Exceptional article in the Observer

Today's Observer tells us this:

Gifted pupils: too many are just ordinary, say teachers
Whitehall estimates that one-in-10 children have exceptional talent are far too high, reveals study
Well, um, yes.

The obvious question is why 10%? There will be a lot of student who are just below this threshold, so are only marginally less exceptional. Why leave them out?

Of course, there are some children who certainly do not have exceptional talent (e.g. special needs pupils), so not every pupil should be categorised as exceptional. But with a judicious bit of mission creep, we should be able to include the top 99%.