I wouldn't be surprised if abstract thought/problem solving and critical thinking need to be taught quite young to stick. Sort of similar to how much easier it is for young children to learn new languages compared to adults.
I believe so, a large crux of the argument was that true immersion learning becomes much more difficult if not impossible as an adult because while children will just speak to other children normally, an adult will “tone it down” and talk to someone struggling with a new language, ultimately putting the adult at a disadvantage, since the adult might not hear as much natural language in the new tongue.
Just having the social, familial, and cultural freedom and encouragement to practice abstract thought would be an important first step, otherwise the teaching isn’t very effective.
