I'm guessing you haven't heard of Goodhart's Law? (https://en.wikipedia.org/wiki/Goodhart%27s_law) Under your proposal, surgeons will be incentivized to selectively operate on easier patients and minimize their complication rates while not performing surgery on very sick patients who may also need the same surgery.
Different surgeons in different areas treat different kinds of patients. It's hard to accurately measure anything in a meaningful way that should influence decision making. To use your example, surgeon Z may also perform procedure Y but has (N-5)% of patients reporting relief and (M+5)% of patients reporting post-op complications. However, surgeon Z works at a community hospital and treats a poorer patient population with more co-morbidities. Can you really say if surgeon X is better than surgeon Z?
Different surgeons in different areas treat different kinds of patients. It's hard to accurately measure anything in a meaningful way that should influence decision making. To use your example, surgeon Z may also perform procedure Y but has (N-5)% of patients reporting relief and (M+5)% of patients reporting post-op complications. However, surgeon Z works at a community hospital and treats a poorer patient population with more co-morbidities. Can you really say if surgeon X is better than surgeon Z?