Curriculum, most especially through 6th grade, is driven very much what whatever fad catches hold in the education establishment. It changes every 2 - 3 years. It's really just a symptom that there is very little accountability for the people making these decisions. Put out a curriculum with poor results? Who's going to notice? If anyone does, who will have the power to do something about it?
Do you think that is only a problem in government? Fads are a fundamental part of human nature.
In tech, we have many examples: Agile, Ruby on Rails, React, RISC, OOP, microservices, and so on and so on. All have some real benefits, but also have or have had huge hype cycles.
You can make the same argument for most other industries (if not all of them). And then there are things like diets, religions, etc.
School boards and other elected officials get voted out. Not every time, but businesses that latch onto fads don't fail every time either, as anyone can see.
