It's a bit of a pattern with the CIA.
But I don't think Powell deflected the blame. It was him standing there at the UN. It was his reputation that was persuasive. He had to make sure he was right. It was right that he accepted responsibility, which he did.
He wasn't alone, by the way. The UK's foreign secretary, Jack Straw, gave the speech of his life in support of the war. He was also damaged by the mistake.
There clearly were people who knew there was a lot of lying going on. I don't think it was Powell. It seemed like it was Cheney at the time.