The process of dumbing down was begun in the 1970s, long before the end of the Soviet Union.
It was done because the fears were no longer an attack by the U.S.S.R. but internally. The fears were of brilliant young people who could and would challenge the disparities in society, expose the lies, the tricks, the corruption.
By the 70s The Baby Boomers had graduated University, were entering society, finding jobs, getting married, having children. They were swamped by life so did not have endless time to confront political events.
Further, the end of the War in Vietnam, the legalisation of Abortion, the new attitude towards homosexuality, and the belief that racial issues were being solved, lulled them into a sense of ‘victory.’
Quietly, in slow steps, it was the children of these Baby Boomers who were the target of what can be termed dumbing down.