> Rudolph Steiner has some, let's say idiosyncratic, theories of child development, but I think his basic thesis that children don't need to learn reading, writing, and maths, before their brains are ready for that information, is sound.

FWIW that belief is considered basic developmental science in Germany and informs the early education system there (at least). Maria Montessori was inspired by his work and her system seems for whatever reason to be more accepted in the US.

I was on the school board of a German language school in the US and some of the American parents were frustrated at their kids not being drilled from age 4 or 5 (typically they had a German-speaking spouse who didn't understand that Gadgrind expectation). All the kids, to the best of my knowledge, came out fine but they all of course had parents who could afford (or whose companies could afford) to pay for private schooling so it's the worst of anecdote vs data.

Also all the teachers had masters' degrees, which is unusual in the US but I don't know if that was the result of the German government's selection or was par for the course.