DA - What happened is that she pulled a genre switch halfway through the series and the world-building that she'd set up initially, which was fine for a Dahl-esque boarding school adventure with wizards, suddenly either had Unfortunate Implications or just didn't make any damn sense in the more complex world she was now trying to write. Rowling doesn't really have the writing chops to reconcile the tone shift, but she also didn't try that hard to do so. And that seems to be more down to intellectual laziness on her part? She either doesn't understand or doesn't care that there's a difference between dropping an anvil on Wile E. Coyote in a Bugs Bunny cartoon and dropping an anvil on Oz on Buffy the Vampire Slayer. You can see this in the main stories, but it's really obvious in the "world building" she's done since the series ended.