My 8 and 10 year old are on normal YouTube a lot and screen in general and they’re excelling in elementary school.

But before school ages I socialized with them constantly. Built Legos, showed them SnapCircuits, read books, danced to music and used basic instruments, helped them with basic cooking like measure of ingredients.

It has nothing to do with screen and YouTube and everything to do with hands on practice across contexts.

Non-verbal, inept kids who did not get hands on mentorship have existed forever. There are more ignorant, inept parents in the world than geniuses. In the US only 14% of the public has more than a bachelors while polls suggest public believes it’s closer to 45%-50%

Like much of the world the majority in the US just aren’t that intelligent.