Bertie the Bunyip writes:

That I an believe. But it would be pitched towards a 12 year old
education/maturity level, not IQ, I would imagine.

Actually, there are good reasons for developing materials for lower IQs.

The average IQ is 100. Half the population is above that ... and half of it
is below. If you develop material that requires an average IQ to understand,
half of the population will not understand it. For this reason, it makes more
sense to develop material for a lower target IQ, so that a much larger
percentage of the population can handle it. If you target an IQ of 70, for
example, about 98% of the population will be able to understand it. This is
the reason for "dumbing down" materials to the lowest common denominator
(within reason).

In commercial endeavors, you dumb down your advertising and other materials
until everyone with the money to buy your product or service can understand
it. In politics, you dumb down your rhetoric and policy until everyone with
the ability to vote can understand it.