This is complete claptrap.
One of the most successful series of children's books of modern times has been Harry Potter. Note its Harry, not Harriet. I don't know for sure but I suspect more girls have read Harry Potter than boys, just because more girls read books than boys. But any teacher will tell you that its been instrumental in getting boys to read books, always a difficult task.
When I was growing up, us boys read Biggles, Jennings, Billy Bunter, and the wonderful Just William. If these books had had a girl as the protagonist they would have remained firmly on the shelf. Nor did us boys feel the remotest interest in reading about ponies or what happened at Malory Towers.
Boys and girls are both children but they are not the same, and wishful thinking by a lot of feminists stricken with penis envy isn't going to change things.
I bet I have put the cat amongst the pigeons now !