Dumbledore is not a saint. He is the man who knew, knew and told Harry that he was sentencing Harry to ten hard years, when he left him at the Dursley's house. In those ten years,arge set a dog on him, they kept him in a closet, Petunia swing a frying pan at his head, Dudley and his cronies created Harry hunting, at on short rations, without even clothes of his own.
Those are just the things mentioned in Canon; how many other events were not written of?
No, Dumbledore is directly responsible for the abuse Harry suffered; if he hadn't left him there, Harry wouldn't have gone through that.
No, Dumbledore is just a man, one with too many responsibilities, who doesn't or didn't understand that setting an orphan's possessions on fire, or even pretending to, isn't going to teach them anything but might makes right.
Riddle had issues before Dumbledore's visit; that display didn't help any.
Dumbledore made mistakes, and his insistence on trying to save people led to the worst Dark Lord ever. Anytime before the prophecy he could have killed Riddle, after he came out as Voldemort; but he chose to not do so. He bears some measure of responsibility for every death of the Voldemort wars.
And the worst bit? Forty years of wars, and nothing changed. Malfoy got off, just as his daddy did, the purebloods still treat muggles like shit, (witnessed by Ron confounding the license person to get his pass, on a driving test, something far too many idiots can do, judging by the number of autopsies I have done on people driving stupid.)
All the fear, the horrors, the deaths, and nothing changed.