The whole "Education" thing is definitely a part of it.
But it started before the 1990's.
Back when Uncle Johnny was a lad and still a prisoner of the public school system's inhouse suspension pipeline, he saw a definite shift in education.
History had been nothing but "BOOM! FACTS! This is what happened." and educated all the way up the Korean War and what led to Vietnam in the 1950's and early 60's (Where out textbooks ended). The older teachers *might* talk about WW2 or Korea a little closer. We also learned about what was going down in Europe and around the world.
Imagine learning about the Boxer Rebellion in Elementary School!
Then, these younger teachers started coming in, and our 10+ year old textbooks were mass replaced. (Remember "New Math"? Remember trying to get Americans onto the Metric System? Uncle Johnny does)
The younger teachers HATED America. It started focusing on all the shit we did wrong. Telling us how we should feel and what conclusions we should draw.
Rather than show us films and slideshows on the Trail of Tears and the Indian Wars and learning all about them (How Custer was a LOLCow who should have NEVER been put in charge of a fucking potato peeling duty much less the 7th Cav Regiment) from several angles, including having a local Native American speaker come in, there was a few short paragraphs that just told you White Settlers Bad, Native Americans Good.
Which was funny, considering you could just go down to the park and see the old Cav Fort with all the scars from the Indian attacks.
We learned more about Jane Fonda's part in the Vietnam War and how it was all about "Oppressing people in the name of European Supremacy and Colonialism" than about how the French had gotten us into a SECOND fucking war after WW2 to try to keep one of the colonies they fucking abused the shit out of.
Suddenly, everything became about how the USA caused it all and was the worst country on Earth.
No more were we learning how the complex treaties and compacts and agreements led to WW1, now apparently it was over a fucking "Revolutionary" killing an Arch-Duke who was oppressing his people and that's why WW1 happened.
Two paragraphs, if you were lucky, and that's IF the teacher didn't skip it.
Christopher Columbus? Fuck him. You're going to learn nothing but he took back slaves and everyone rushed America to steal the land and resources for no other reason than white people.
Rome? Nigga, you ain't learning about that. This is HISTORY, not History.
World War 2? The Japanese wouldn't have attacked us except we were being belligerent and not giving them the oil and steel they needed and so they sent a diplomat to warn us and he was forced to wait to meet the President! WW2 could have been avoided!
THis was WAY before the 1990's.
Remember, boys and girls, the American Revolution happened because a bunch of rich white slave owners didn't want to pay their taxes.
Oh, you'd spend TWO FUCKING MONTHS on the Civil Rights movement, how blacks were oppressed, how slavery was the worst thing ever and white people caused it all.
Would you learn about the Civil War beyond "Evil whites want to keep their slaves and other evil whites didn't want slaves to compete with factories and the poor black man was caught in the middle?" LOL Nope.
Education has been FUCKED since the 70's.