There’s been a lot of talk about how bad a headmaster Dumbledore was.
He routinely hired incompetent and evil teachers, he regularly cancelled exams, he didn’t interfere with teachers straight-up bullying their students except when the students being bullied were his personal favorites (namely Harry, though likely also the Mauraders, Hagrid, and a young Tom Riddle).
And you know what? It makes perfect sense.
Because Dumbledore never for an instant thought of himself as a teacher or a headmaster. Hogwarts wasn’t the place he wanted to be, it was his personal place of exile, to keep himself from taking over the world alongside his ex-boyfriend.
He saw himself as a puppetmaster and a general, and all of his decisions reflected that.