Also, the Dunning-Kruger effect still applies to smart people. You don't stop when you are estimating your ability correctly; as you learn more, you gain more awareness of your ignorance and continue being conservative with your self-estimates.
Performative behavior is not a modern phenomenon. Deceitfulness is so effective we're not going to end it by discussing Dunning-Kruger every chance we get. Mere knowledge is not enough to defeat it, and you'll always be sorry when you underestimate your opponents.
It's all ultimately a matter of trust, and that takes time most people don't have or don't want to give. It's more important to stack incentives to compel behavior and hedge your bets against people who seem off.