A firm's reason to be chosen has to be invented.
Two firms with comparable people and comparable methods will not win at the same rate. Someone at one of them decided what the firm believes, who it is for and why that matters now, then found out in the market whether the decision was any good.
Most firms buy that invention and its execution from different people. A brand agency writes a story it has never sold. A sales consultant improves a story they did not write. In between, the idea degrades.