But it is accurate, to an extent. Shakespearean tragedies have this tendency of interspersing comical characters and moments of laughters in between the hefty goings-on and the dark destinies. It provides a contrast to, and heightens, the tragic events. Think of the graverobber scene just before Hamlet finds out Ophelia is dead, or The Porter just after Duncan's murder. Yes, I am overstating the point, and no I wouldn't compare Rowling's writing per se to Shakespeare's. But the mixing of genres is definitely there. The book has a very clear tragedy structure. It has all the components, from fatal flaws galore to peripeteic twists and anagnorisis. But it is littered with comedy.