Same thing about the first book being the reason I learned how to read lol. I didn't want to wait for other people to read it to me anymore. But the setting probably has a lot to do with it. As an American who went to small schools, even the idea of grounds was cool and exciting. Houses were new and, I thought for many years, not a thing in the real world. All that paired with magic and brooms and the idea of an entire unexplored world sitting under our noses hooked me hard as a kid. I don't even really like low fantasy as a general rule, but this was one of the only exceptions to that. The other was the Xanth series by Piers Anthony, but that entire magic system was based on puns and only dipped into the real world rarely so I give it a pass.