I started reading the baby sitters club in third grade, just like half the other little girls in America. So I was 8, and Kristy and the gang were 13. If I had waited until I was their age, the series would have been cheesy and laughable. (Ok, I probably did still read them when I was their age, despite the cheese. Just the Super Specials! They were my old friends by then, how could I leave them behind?)
As it was, it was a series that helped me fall in love with reading. The girls were so cool and free, and I felt like I knew them, even though their "chic" outfits and babysitting jobs were totally outside my own elementary school experience.
The same goes for a Wrinkle in Time. Meg was 14, and I couldn't have been older than 9 or 10 when I fell in love with that book. I re-visited it many times over the years, and I undoubtedly gleaned more from it every time I read it. But to be denied those years of pleasure because Meg was 14 and I was too young to appreciate some aspects of the story? It would have been a shame.
Nearly every book M reads is about someone twice his age or more. What matters to him is the story, the words, and the feeling of being transported to another place. Horrible Harry and Junie B will never have any appeal for a child like him who has tasted true writing.
It's not that I don't want him to read books about kids his age. There just aren't many at his level. And chances are, if there is a great book about a kid his age- he's read it!
In the end, I think that rule is just abritrary. Someone made it up, and it sounds good, and it fits for a lot of kids, so they pass it on. Plus, then they can feel smug when they see someone else's kid reading a book they are "too young for." No one is using any critical thinking skills or drawing on their own childhood experience.
Look at Roald Dahl- Matilda is a kindergartner, Danny is 9, Charlie is 11, James is around 7, and the fantastic Mr. Fox is an adult.... fox. Surely a child could enjoy all his books in the same season.
I know it's trendy right now to brag that your child won't read Harry Potter until his eleventh birthday or to claim that books are robbed of their specialness when they are read too early.
Books are special. But strong readers like M can appreciate their specialness now and be shaped by them from an early age. Why shouldn't they?