Well. Upper tenth is just one in ten. Chances are blazing insights in that region are going to be ideas that have been had and discarded by a near a billion other people.

Whatever percentile the intellect, blazing insights are likely to be high variance ideas because they exist at the edge of the thinkers capacity. The implication is that most insights are wrong or poorly understood, as such they will be hard to explain.

It is the things that you take for granted that you truly understand and can explain, you'll just be surprised at the need. But to someone else who has less a gift for abstraction your explanation will seem a profound insight.