For better or worse, testing was used as an assortative matching between students and universities they applied for. Though far from perfect, a university that set their acceptance bar at a certain level could expect incoming students to at least be at or around that level.

The less rigorous the filtering, the more you have to accommodate the lower ends of the incoming students’ abilities. So as standardized testing is softened, so too is the curriculum that students are exposed to.

There is a movement against standardized testing that gained traction in the past decade, arguing that because it’s flawed and imperfect we should abandon it. The movement never had a good replacement for it, though, so the shift was toward looser standards and judging students based on vibes and non-academic measures. Many of the universities that went this direction are reversing course and adding standardized testing back now because the reality of higher education is that you need to filter incoming students by some academic measurements if you want to be able raise the bar for your curriculum.

The effects cascade everywhere. In a perfect utopia everyone would get individualized perfect tutoring and we wouldn’t have to worry about testing, but in the world we inhabit a lot of the education decisions and realities are downstream of what we can test for.