Except the very first thing Dumbledore plan we the readers get to see executed, in the very first book, is his "trap" for Quirrel, where he doesn't notice Quirrel being possessed by Voldemort and lets him unmonitored access to the student body for an entire year (including a murder attempt), sets up the main goal for voldemort to be hidden in a school behind a series of traps solvable by a bunch of first years that just happen to all be close friends/allies of TBWL, sets up his close comrade Hagrid, who he knows cannot keep a secret to save his life, to be party to a whole list of important information so that information can be leaked to the first years/villain, and then, and then, when he knows things are coming to a head at the end of the school year (because "the thing murdering unicorns and drinking their blood in the forest" which he also sent first years out to find with Hagrid as their only backup) he fucks off to London *by broom* apparently to let the whole thing play out without his supervision.
Dumbledore is an enormous manipulator who chessmastered the entire first book on purpose and the only reason nobody got hurt throughout the entire year was a staggering quantity of blind luck. Hermione could have died if Ron and Harry hadn't decided to go hunt her down during the troll attack, there's no reason for snape to not know how to calm fluffy other than red herring points, and again, Quirrel, who was possessed by Voldemort the whole year, was just lose to do whatever. What if he decided to blow up the whole third floor corridor, or mind control a bunch of students to test the defenses, or tried to murder Harry in a place other than "in front of the entire school during sports". This is what people extrapolate off of when they come up with "manipulative dumbledore". HE thinks he is right, thinks his plans are foolproof, and implements them without telling anyone else or having any backups for if something goes wrong. Fuck, what if Quirrelmort attacks Malfoy instead of just starring at Harry when they encounter him in the forest, or the Centaurs don't show up. Dumble sure would be out of a job in minutes if he got Draco killed in detention.
