I'd suggest there is a difference between parenting advice, and information about how children develop physically and mentally.

Sure, any jerk on the street can offer advice on parenting.

But humans are physical, deterministic meat machines. They work in a certain way, and that way does not change over a decade or two. The technology surrounding us does, but not the human. And there are people who study how humans work. It's worth listening to them on that subject.