I do think that this is a huge factor. There's somebody in that thread who claims to be a pre-k teacher, and mentions that things like days of the week, colors, shapes, etc. have been removed from the pre-k curriculum for being "developmentally inappropriate," but kids are expected to do complex phonics exercises. I teach (mostly) 11th/12th grade in a very weird public school that isn't subject to these trends, but I have friends who teach k-12 in more standard schools that complain a lot about contemporary curriculum design. Everything is decontextualized and disconnected from everything else. The standard English curriculum mostly reads short passages to prepare for standardized tests rather than books. Math is almost entirely problem sets to prepare for standardized tests. None of it is connected to anything else, and teachers really have to go the extra mile to provide any kind of context or explanation for why students are learning the things they are in the order they are (and doing so means less time to teach to the standardized tests, which negatively impacts funding and teacher performance metrics). The insane focus on standardized testing and "metrics" is a problem at almost all levels, and has been an unmitigated disaster for educational performance. The purpose of all of this, of course, is to mold kids into ideal wage slaves for our billionaire overlords, which is why contemporary curriculum focuses so heavily on drilling mechanical skills and test performance rather than a broad understanding of the natural world and our place in it. No Child Left Behind and its successors have been a catastrophe.