In game theory we think about incentives mattering in a way that makes sense, indeed incentives are the heart of game theory we're trying to explain peoples behavior in terms of their own incentives and how they interact with other people's incentives, and one of the important messages that mixed strategy Nash equilibrium tells us is that sometimes our intuition about how players respond in equilibrium to changes, some things our intuition doesn't serve us as well as we'd think and when the  Equilibrium is a mixed strategy 