In Sanderson's super school book, there are 10 kids and only one of them is uninterested in piloting spacefighters. But he is interested in engineering, so he's still able to be a big nerd about the book's subject matter. Everyone else is either a great pilot who likes piloting, or fucking dies in a tragic scheme emphasising the brutality and pointlessness of war.
Sanderson doesn't write characters who just drift along without an interest in anything, because Sanderson writes books about topics that he makes interesting.
Rowling is only able to create characters who think Divination or History of Magic are boring, because she makes them boring. Sometimes on purpose!
You know what? Rowling did actually follow Sanderson's laws with one specific bit of magic. The time turner. The time turner has a very simple limitation: you cannot change the past. But, you can do things in the past that don't change what you experienced the first time. We understand how the time turner works, and Rowling comes up with a clever way to make it work, which makes sense to us. That's the second and first law! The time turner is well written!
And then she broke the third rule. She didn't expand on it, she added something new in book 4 instead. So people asked "what about the time turner", and in the next book she got mad and destroyed them all so she'd never be asked "what about the time turner" again.
Rowling wrote something really interesting that actually makes sense. And then decided she didn't want it in her story anymore. Because Rowling doesn't actually like writing interesting magic. And that's why Harry and Ron aren't very interested in magic. Rowling was never able to write a scene where a character actually geeks out about how magic works, because she doesn't care how it works. She's not interested.