Idk, my oldest kid is 10 and has finished the whole series. She may have intended kids to grow with the series, and that was certainly true when they came out (I remember my cousin reading the books as they came out), but I do think they have limited appeal to more mature audiences.

That said, I do still read YA novels, and I’m definitely not the audience, so I’m sure there are plenty of older kids and adults who aren’t as bothered by plot holes and whatnot.