Just to amplify that, there has to be a reason that Rowling!Voldemort hides on the back of Q’s head. (Ok, the meta-reason might be that Rowling just thought this would be really creepy and didn’t think about what would actually be smart for V to do, but that’s Rowling!Potterverse all over: brilliant façade, nothing behind it.) So that reason, even if EY has to invent it on Rowling’s behalf (“Rowling!V is stupid” isn’t good enough), has to still apply. For EY!Voldemort to be in control of Quirrell some other way cannot be justified just by saying that EY!V is smarter and found a way. Specific differences need specific explanations.
When Dumbledore is entertaining the possibility that shade!Voldemort possessed Hermione he doesn’t say “But we know that’s not the case because the back of her head isn’t deformed.”
More generally, there’s been lots and lots of specific changes to how magic in general and certain magics in particular work. Forex: in canon there’s no such thing as “magical exhaustion”. Basically everything about Transfiguration is different. Combat is different, and far more detailed.
I took that particular passage as evidence that Rational!Voldemort is not so incompetent as to risk discovery through hat-removal.
I reject this explanation simply because it isn’t an interesting explanation.
Just to amplify that, there has to be a reason that Rowling!Voldemort hides on the back of Q’s head. (Ok, the meta-reason might be that Rowling just thought this would be really creepy and didn’t think about what would actually be smart for V to do, but that’s Rowling!Potterverse all over: brilliant façade, nothing behind it.) So that reason, even if EY has to invent it on Rowling’s behalf (“Rowling!V is stupid” isn’t good enough), has to still apply. For EY!Voldemort to be in control of Quirrell some other way cannot be justified just by saying that EY!V is smarter and found a way. Specific differences need specific explanations.
When Dumbledore is entertaining the possibility that shade!Voldemort possessed Hermione he doesn’t say “But we know that’s not the case because the back of her head isn’t deformed.”
More generally, there’s been lots and lots of specific changes to how magic in general and certain magics in particular work. Forex: in canon there’s no such thing as “magical exhaustion”. Basically everything about Transfiguration is different. Combat is different, and far more detailed.