You can use the code I posted there to do a similar analysis for any story - is there a story of yours that you’d like to try?

As to your overall point - I think it’s always true. The rules are always merely guidelines, and if you’ve got a good reason you should break them rather than be constrained.

An interesting development that evolved from the Harry Potter series is that young readers began to demand more “grown up” writing. I worked in a bookstore during the long wait between the third and fourth book of the series. The children who were 9 and above were disgusted with the books aimed for their presumed reading ability. They were insulted by the simple language and began to read science fiction from the adult department.

Side note: some American publishers have actual lists of “age appropriate” words that can be used in writing for specific grades. Needless to say, these are the simplest words possible. British writers and publishers appear to have a higher opinion of children’s ability to learn how to read at a higher level.