It became obvious in the 1980s. That's when public schools started saying "let's prep our kids for SATs, too, so they're not excluded for low scores." My first Math SAT Prep I taught was in 1985. Scores compared to the PSAT went up an average of just over 100 points in Math, about 70 in English. It doesn't sound possible, I know. There was absolutely no information before then about test taking or identifying basic skills to be perfected, so there was a lot of room for improvement.. Even back then, it didn't get them those top-tier acceptances. But it did get a lot of them very excellent scholarships (not loans) at second tier schools.
It was (and still is) a middle class working mostly white community.
That was over 30 years ago. This has been a war against the successful and motivated white middle class the US used to have. There's a whole lot of outrage built up. Perhaps the result of this will be to say that "elite" school diplomas will be a question mark about integrity instead of a golden ticket to the future.
The "outrage" you describe is misdirected. This outrage should have motivated parents to stop playing the stupid game of pushing their kids into ridiculously expensive schools where the education was no better than what they'd get at a second-tier or even third-tier school.
What you're describing isn't the outrage of people who really have a legitimate complaint. It's the outrage of people who have been conned for a long time and still haven't figured it out.